Download Study material of Science for class X

KENDRIYA VIDYALAYA CHENANI
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Study material of Science for Class –X
Session 2015-16
CHAPTER WISE BLUE PRINT (SA1) Class X SCIENCE
SAMPLE 2
S NO.
CHAPTER
VSA
SA1
SA2
LA
TOTAL
WEIGHTAGE
1(1)
2(2)
2(3)
-
11
2.
Chemical reaction and
equation
Acid, Bases and Salts
2(1)
1(2)
1(3)
1(5)
11
3.
Metals and Non metals
2(1)
-
1(3)
1(5)
10
4.
Life Process
3(1)
1(2)
1(3)
1(5)
13
5.
Control and Coordination
-
-
1(3)
1(5)
08
6.
Electricity
3(1)
1(2)
2(3)
1(5)
16
7.
Magnetic effect of Electric
Current
-
1(2)
2(3)
1(5)
13
8.
Sources of energy
1(1)
-
2(3)
-
7
Total Theory based
Questions
3(1)=3
3(2)=6
12(3)=36
6(5)=30
75(24)
Practical Based Questions
9(1)=9
3(2)=6
-
-
15(12)
TOTAL MARKS
12(1)=12
6(2)=12
12(3)=36
6(5)=30
90(36)
1.
TOTAL QUESTION =36
TOTAL MARKS =90
CHAPTERWISE BLUE PRINT (SA 2) Class X SCIENCE
SAMPLE 1
.NO
CHAPTERS
TOPICS
S NO.
1.
VSA(1)
SA-I(2)
SA-II(3)
LA(5)
TOTAL
CHAPTER
VSA
SA1
SA2
LA
Total marks
chapter wise
Carbon Compounds
3(1)
1(2)
1(3)
1(5)
13
-
1(2)
1(3)
1(5)
10
3(1)
-
2(3)
1(5)
14
-
1(2)
3(3)
1(5)
16
4(1)
1(2)
2(3)
1(5)
17
-
2(2)
1(3)
1(5)
12
1(3)
-
04
-
04
6(5)=30
75(24)
-
15(12)
6(5)=30
90(36)
2.
Periodic classification
3.
Reproduction
4.
Heredity and Evolution
5.
Light
6.
Human Eye
7.
Our Environment
1(1)
-
8.
Management of natural
resources
1(1)
-
Total (Theory Based
Questions)
3(1)=3
3(2)=6
12(3)=36
Practical Based Questions
9(1)=9
3(2)=6
-
12(1)=12
6(2)=12
TOTAL MARKS
1(3)
12(3)=36
TOTAL QUESTIONS =36
TOTAL MARKS =90
1
2
3
4
LIFE PROCESS
Control and
coordination
Nutrition
1
Respiration
1
Transport and excretion in
plants and animals
1
Control and coordination in
animals
1
10
1
1
11
Nervous system
1
Reflex action
1
1
Animals hormones
Tropic movements in plants
Electricity
1
Electric current
1
Potential difference and electric
current
1
Resistance
1
17
1
Ohm’s Law
Heating effects of electric
current and application in daily
life
1
Interrelation between P,V,I and
R
1
Series combination of resistors
and its daily application
1
Or
Parallel combination of resistors
Magnetic
effects of
electric
current
Direct current/ alternating
current
1
12
Flemings left and right hand rule
1
Electromagnetic induction /
potential difference/induced
current
1
1
5
Principle and working of electric
motor/ac generator
Source of
energy
Solar energy / Bio gas
1
7
Renewable vs non – renewable
sources/conventional and non
conventional sources of energy
1
Fossil fuels/solar energy/Nuclear
energy
1
TOPICWISE BLUE PRINT SA II
S.NO
CHAPTERS
TOPICS
VSA(1)
6
Carbon and
compounds
Functional
groups(halogens.alcohols,ketones,al
dehydes , alkenes and alkynes),
homologous nomenclature of
carbon compounds
1+1
SA-I(2)
Chemical properties of carbon
compounds sops/ detergents
LA(5)
1
1
1
1
TOTAL
13
1
Unsaturated and saturated
hydrocarbons
Or
SA-II(3)
7
Periodic
classification
of elements
Need of classification
1
10
Modern periodic table or
Mendeleev’s periodic table
1
Graduation in properties
1
Metallic and non metallic properties
across periods or groups
1
Renewable vs non – renewable
sources/conventional and non
conventional sources of energy
1
1
Fossil fuels/solar energy/Nuclear
energy
8
How do
organism
reproduce
Asexual and sexual reproduction
1+1
17
Hiv aids
Menarch/menopause
1
Method of family planning
1
Vegetative propagation
1
External and internal fertilization
1
Male and female reproductive
system in animals or plants
9
Heredity and
evolution
Heredity/evolution
1
1
13
Mendels law
1
Sex determination in humans
1
1
Concepts of evolutions/ evidences in
favour of evolution
Ecosystem and its component/food
chain/ food web ozone layer and its
depletion, management of garbage
10
Environment
11
Management
of natural
resources
Sustainable management/water
harvesting reduce/ recycle /
reuse/pollution
1
1
UNITWISE BLUE PRINT
1
5
3
.NO
CHAPTERS
TOPICS
VSA(1)
1
LIFE PROCESS
Nutrition
1
Respiration
1
Transport and excretion in
plants and animals
1
Control and coordination in
animals
1
2
3
4
Control and
coordination
SA-I(2)
SA-II(3)
LA(5)
TOTAL
10
1
1
11
Nervous system
1
Reflex action
1
1
Animals hormones
Tropic movements in plants
Electricity
1
Electric current
1
Potential difference and electric
current
1
Resistance
1
17
1
Ohm’s Law
Heating effects of electric
current and application in daily
life
1
Interrelation between P,V,I and
R
1
Series combination of resistors
and its daily application
1
Or
Parallel combination of resistors
Magnetic
effects of
electric
current
Direct current/ alternating
current
1
12
Flemings left and right hand rule
1
Electromagnetic induction /
potential difference/induced
1
1
5
current
Principle and working of electric
motor/ac generator
Source of
energy
Solar energy / Bio gas
1
7
Renewable vs non – renewable
sources/conventional and non
conventional sources of energy
1
Fossil fuels/solar energy/Nuclear
energy
1
TOPICWISE BLUE PRINT SA II
S.NO
CHAPTERS
TOPICS
VSA(1)
6
Carbon and
compounds
Functional
groups(halogens.alcohols,ketones,al
dehydes , alkenes and alkynes),
homologous nomenclature of
carbon compounds
1+1
SA-I(2)
Chemical properties of carbon
LA(5)
1
1
1
1
TOTAL
13
1
Unsaturated and saturated
hydrocarbons
Or
SA-II(3)
compounds sops/ detergents
7
Periodic
classification
of elements
Need of classification
1
10
Modern periodic table or
Mendeleev’s periodic table
1
Graduation in properties
1
Metallic and non metallic properties
across periods or groups
1
Renewable vs non – renewable
sources/conventional and non
conventional sources of energy
1
1
Fossil fuels/solar energy/Nuclear
energy
8
How do
organism
reproduce
Asexual and sexual reproduction
1+1
17
Hiv aids
Menarch/menopause
Method of family planning
1
1
Vegetative propagation
1
External and internal fertilization
1
Male and female reproductive
system in animals or plants
9
Heredity and
evolution
Heredity/evolution
1
1
13
Mendels law
1
Sex determination in humans
1
1
Concepts of evolutions/ evidences in
favour of evolution
Ecosystem and its component/food
chain/ food web ozone layer and its
depletion, management of garbage
10
Environment
11
Management
of natural
resources
Sustainable management/water
harvesting reduce/ recycle /
reuse/pollution
1
1
Biology Activity
Life Processes
Activity 1:- To show that chlorophyll is essential for photosynthesis.
1
5
3
Material Required:- A potted plant of variegated leaf such as money plant, white paper sheet, pencil,
beaker, water bath, iodine solution and alcohol.
Procedure:1. A potted plant with variegated leaves is placed in sunlight for about six hours.
2. Pluck a variegated leaf from the plant and trace the outline of this leaf on a piece of paper.
3. Dip the leaf in boiling water for a few minutes and then immerse it in a beaker containing
alcohol and boil it in a water bath till it decolourises.
4. The leaf is then dipped in a dilute solution of iodine for a few minutes.
5. Take out the leaf and rinse off the iodine solution.
6. Observe the changes in colour of the leaf.
Observation:1. The leaf has two type of patches- bluish black and yellow. The bluish black area contains
starch and the yellow areas without starch.
2. Bluish black areas are the ones, which were green previously, while non-green areas remain
pale coloured.
Conclusion:- This experiment proves that only chlorophyll containing areas i.e., green parts of the
leaf produce starch which is a product of photosynthesis. Thus, chlorophyll is essential for
photosynthesis.
Activity 2:- To show that Carbon dioxide is necessary for photosynthesis.
Material Required:- Two healthy potted plant of same size, two glass plates, two bell jars, Vaseline,
watch glass, potassium hydroxide, alcohol, spirit lamp and beaker.
Procedure:1. Keep the two potted plants of same size, in dark for three days so that the leaves become
free from starch.
2. Place the potted plant(a) on a glass plate and put a watch glass containing potassium
hydroxide(KOH) by the side of the pot and cover it with a bell jar.
3. Place the other potted plant(b) on a second glass plate and cover it with a bell jar.
4. Vaseline is used to seal the bottom jars to the glass plates so that the set up is air-tight.
5. Both the plants are kept in sunlight for two hours.
6. Pluck a leaf from each plant and test the same for the presence of starch.
Observation:- The leaf of plant (b) without potassium hydroxide turns blue-black, while the leaf of
plant (a) with potassium hydroxide remains pale coloured or colourless.
Conclusion:- This experiment demonstrate that the leaf plant(b) has synthesized starch with the help
of photosynthesis and leaf of plant (a) has not synthesized starch as it does not contain carbon
dioxide as the same is absorbed by potassium hydroxide. So, photosynthesis did not occur in (a)
Activity 3:- To show that carbon dioxide is produced during respiration.
Material Required:- Two test-tubes, freshly prepared lime water, syringe or pichkari, rubber tube
and a glass tube.
Procedure:-
1. Pour freshly prepared lime water in each test-tube (A & B)
2. Blow air in test- tube B through the lime water with the help of glass tube.
3. Pass air through lime water in tube A with the help of a syringe or pichkari fitted with a fine
rubber tube.
Observation:-
1. Lime water turns milky in tube B showing that we exhale carbon dioxide.
2. In tube A, lime water take long time to turns milky.
Conclusion:-
1. Lime water turns milky when carbon dioxide mixes with it.
2. Air blown out from mouth contain carbon dioxide.
Control and Co-ordination
Activity 1:- Response of the plant to the direction of light.
Requirements:- Conical flask, water, wire mesh, 2-3 freshly germinated bean seeds, cardboard box
open from one side.
Method:- Take a conical flask and fill it with water. Cover the neck of the flask with a wire mesh.
Now, keep two or three freshly germinated seeds on the wire mesh. Keep this flask in the cardboard
box(open from one side) in such a manner that the open side of the box faces light coming from the
window. Observe the plant after few days. Now, turn the flask so that the shoots are away from light
and the roots towards light. Leave it undisturbed in this position for a few days and then observe the
difference if any.
Observations:-
1. When the flask is placed in the cardboard (open from one side) in a manner that the open
side of box faces light coming from the window, the shoots of freshly germinated seeds have
shown growth by bending towards light(positive phototaxis) and roots have shown growth
by bending away from light( negative phototaxis)
2. When the flask was turned in a manner that the shoots moved away from light and roots
moved towards light, you will fid after few days that the shoots have again grown by bending
towards light and the roots have grown again by bending away from light.
This experiment, therefore, shows that the shoots of plants respond by showing growth
movement towards light(positive phototropism) and roots of plants respond by showing
growth movement away from light (negative phototropism)
Activity 2:- Action of Gustatoreceptors and Olfactoreceptors.
 Put some sugar in your mouth. How does it taste?
 Block your nose by pressing it between your thumb and index finger. Now eat sugar again. Is
there any difference in its taste?
 While eating lunch, block your nose in the same way and notice if you can fully appreciate
the taste of the food you are eating.
Observations:1. When we put sugar in our mouth, it tastes sweet.
2. When we eat sugar after blocking our nose by pressing it between thumb and index finger,
we find no difference in its taste.
3. While eating lunch, when we block our nose by pressing it between thumb and index finger,
we find that we cannot fully appreciate the taste of food.
Explanation and Conclusion:1. Gustatoreceptors are present in specific regions of tongue in our mouth. They respond to
taste stimulus. When we eat sugar, these gustatoreceptors get stimulated and send message
in the form of nerve impulses to specific region of brain. Here, information is interpreted and
we feel sweet taste of sugar.
2. When we eat sugar after blocking our nose, we still find no difference in its taste. It is so
because pressing of nose blocks stimulation of olfactoreceptors which are sensitive to smell.
However, Gustatoreceptors, present in the tongue, get stimulated when these come in
contact with sugar.
3. The food we normally eat during lunch contains both tasty and aromatic substances. These
stimulate Gustatoreceptors(present in tongue) and olfactoreceptors(present in nose). Thus,
we appreciate fully the taste of food. When we block our nose, while eating lunch, the
olfactoreceptors are not stimulated. Hence, we can not feel smell of food. However, we feel
the taste of food since Gustatoreceptors get stimulated on coming in contact with food.
Thus, we cannot fully appreciate the taste of food.
How do Organisms Reproduce
Activity 1:- To examine growth of bread mould fungus (Rhizopus) on the moist slice of bread.
Requirement:- Moist slice of bread, Petridish, magnifying glass.
Method:- Wet a slice of bread in water and place it in a petridish or watch glass. Keep the moist slice
of bread in a cool and dark place for 1-2 days. Observe the slice with the help of a magnifying
glass.
Observations and Conclusion:- A white cottony mass appears on the surface of moist bread which
turns black within few days. The white cottony mass is due to growth of bread mould (Rhizopus).
The spores of fungus are present in the air. They settle on the moist bread and germinate to form
white cottony mass of vegetative mycelium. The vegetative mycelium develops asexual
sporangia which are black in colour. Each sporangium contains hundreds of minute blackcoloured spores. These spores are dispersed in air to germinate on suitable substratum.
Activity 2:- To observe the different parts of seed.
Method:- Soak a few seeds of Bengal gram(Chana)in a beaker and keep them overnight. Decant
excess water and keep the seeds in a wet cloth. Leave them for a day. Now the seeds get
germinated by giving out a few mm of radicle. Cut open the seeds carefully to observe the
different parts.
Observation:- Observe the brown coloured testa that encloses two cotyledons laden with stored
food material. A small embryo consisting of radicle and plumuls lies in between the two
cotyledons.
Heredity and Evolution
Activity 1:- Observe the ears of all the students in the class.
Method:- Prepare a list of students having free or attached ear lobes and calculate the percentage of
students having each. Find out about the ear lobes of the parents of each student in the class.
Correlate the ear lobe type of each student with that of their parents. Based on this evidence,
suggest a possible rule for the inheritance of ear lobe types.
Discussion and conclusion:- Presence of free ear lobes and attached ear lobes is an example of
variation in Human population. The observations recorded by you will reveal that vast majority of
the students of your class and their parents have free ear lobes.
Chemistry activities for class 10th
Chemical reactions and equations
1.To show the characteristics of a chemical reaction

Take few zinc granulesin a conical flask or a test tube.

Add dilute hydrochloric acid or sulphuric acid to this.

we observe a brisk effervescense.

Touch the conical flask or test tube the flask becomes hot.

Conclusion- The chemical reaction may be characterized by evolution of a gas,
change in energy, change in colour or formation of precipitate.
2.To show combination reaction of CaO with water.




1.Take a small amount of calcium oxide or quick lime in a beaker.
2.Slowly add water to this.
3.Touch the beaker the beaker becomes hot as a large amount of heat is evolved.
Conclusion-The reaction of calcium oxide with water is exothermic.
3. Action of heat on FeSo4 crystals.





1.Take about 2g ferrous sulphate crystals in a dry boiling tube.
2. Note the colour of the ferrous sulphate crystals.
Heat the boiling tube over the flame of a burner or spirit lamp.
Observe the colour of the crystals after heating .The colour becomes white.
Conclusion-Ferrous sulphate on heating gives out water of crystallization and
becomes anhydrous.
4. Action of sunlight on AgCl.




Take about 2g of silver chloride in a china dish.
Place this china dish in sunlight for some time.
Observe the colour of silver chloride after some time.
Conclusion-On exposing AgCl to sunlight decomposition reaction takes place and
silver chloride breaks down to produce silver and chlorine gas is released.
5.Reaction of iron nails with copper sulphate solution.


Take three iron nails and clean them by rubbing sand paper.
Take 2 test tubes marked as (A) and (B). In each test tube, take about 10 ml
copper sulphate solution.





Tie two iron nails with a thread and immerse them carefully in a copper sulphate
solution in test tube (B) for about 20 mins. Keep one iron nail aside for
comparison.
After 20 mins. take out the iron nails from the copper sulphate solution.
Compare the intensity of the blue colour of the copper sulphate in test tubes (A)
and (B).
Also compare the colour of iron nails dipped in the copper sulphate solution.
Conclusion-Since iron is more reactive than copper it displaces copper from
copper sulphate. The blue colour of copper sulphate changes to green because of
formation of ferrous sulphate and reddish brown deposit of copper is formed
over iron nails .The intensity of blue colour in test tube (B) is less.
6.Reaction of Na2 SO4 and BaCl2
 Take about 3ml of sodium sulphate solution in a test tube.
 In another test tube. Take about 3ml of barium chloride solution.
 Mix the two solutions
 A white precipitate is formed.
 Conclusion- This is an example of double decomposition reaction in which
barium sulphate forms a precipitate.
7. To show the oxidation of copper.



Heat a china dish containing about 1g of copper powder.
Copper combines with oxygen to form copper oxide which is black in colour.
Conclusion- This is an example of combination reaction
8. Reaction between PbNO3 and KI




Take lead nitrate solution in a test tube.
Add potassium iodide solution to this.
Yellow precipitate is formed
Conclusion-The reaction is an example of double decomposition reaction in
which lead iodide forms a yellow precipitate.
Acid,Bases and salts.
1.To study properties of acid and bases by their actionwithlitmus ( red and blue) paper,
phenolphthalein solution andmethyl orange.




Collect hydrochloric acid, sulphuric acid, nitric acid, acetic acid, sodium hydroxide
calcium hydroxide, potassium hydroxide, magnesium hydroxide and ammonium
hydroxide.
put a drop of each of above solutions on a watch-glass and test with a drop of the
following indicators.
what change in colour do you observe with red litmus,blue litmus, phenolphthalein
and methyl orange solutions for each of the solutions taken.
Conclusion- acids change blue litmus red,bases red litmus blue ,bases change
phenolphthalein solution to pink .
2.Reaction of Zinc granules with dilute H2SO4 and testing H2 gas by burning.



Take about 5ml of dilute sulphuric acid in a test tube and add a few pieces of zinc
granules to it.
Test the gas evolved by bringing the burning splinter.
Conclusion-The gas burns with a pop sound and puts off the burning splinter. The gas
is hydrogen.
3.Passing of CO2 through Ca(OH)2





Take 2 test tubes. Label them as (A) and (B).
Take about 0.5 g of sodium carbonate in test tube (A) and about 0.5 g of sodium
hydrocarbonate in test tube(B).
Add about 2ml of dilute HCl to both the test tubes.
Pass the gas produced in each case through lime water.
Conclusion-The gas produced is carbon dioxide which turns lime water milky.
4. Reaction between acid and base.






Take about 2ml of dilute NaOH solution in a test tube and add two drops of
phenolphthalein solution.
The colour of solution becomes dark pink.
Add dilute HCl to the above solution drop by drop.
We observe that the solution becomes colourless.
It is concluded that colour changes on addition of acid because base is neutralized by
acid.
Conclusion- If we add a drop of sodium hydroxide the pink colour re-appears
because there is excess base in the solution.
5. Reaction of metallic oxides with acids.
 Take a small amount of copper oxide in a beaker and add dilute hydrochloric acid
slowly while stirring.

We observe that the colour of the solution becomes blue-green and the copper
oxide dissolves.
 Conclusion- The blue-green colour of the solution is due to the formation of copper
(ii) chloride in a reaction.
6. Dilution of acid.

Take 10 ml of water in a beaker.

Add a few drops of concentrated H2SO4 to it and swirl the beaker slowly.

Touch the base of the beaker.

We observe that the solution becomes warm.

Conclusion- It is concluded that dilution of an acid is an exothermic reaction.
7.To test the pH of different solutions with the help ofpH paper.
 Test the pH values of the solutions given in table.
 Conclusion- If pH is less then 7, the solution is acidic.
 If pH is 7 then the solution is neutral.
 If pH is more than 7 the solution is base.
s.no. Solution
1.
Saliva (before meal)
2.
Saliva (after meal)
3.
Lemon juice
4.
Colourless aerated drink
5.
Carrot juice
6.
Coffee
7.
Tomato juice
8.
Tap water
9.
1m NaOH
10.
1m HCl
8.Testing the pH of soil.
COLOUR OF
pH paper
Approx. pH
values
Nature of
substance.




Put about 2g soil in a test tube and add 5ml of water to it.
Shake the contents of the test tube.
Filter the contents and collect the filtrate in a test tube.
Check the pH of this filtrate with the help of universal indicator paper.
9.Heating of CuSO4 crystals water ofcrystallization.
 Heat a few crystals of copper sulphate in a dry boiling tube.
 We observe that the colour of the copper sulphate crystals becomes white.
 We notice water droplets in the boiling tube.
 Add 2-3 drops of water on the sample of coppersulphate obtained after heating.
 We observe that the blue colour of crystals re-stored.
 This shows that copper sulphate crystals which seems to be dry contain water of
crystallization.
 When we heat the crystals,this water is removed and the salt turns white.
 If we moisten the crystals again with water the blue colour of crystals re- appears.
 Conclusion- on heating copper sulphate , water of crystallization is given out and the
salt becomes white. When water is added crystals again becomes blue by absorbing water
of crystallization.
PRECAUTIONS WHILE PERFORMING CHEMISTRY ACTIVITIES
Do not touch anything without the permission of the teacherin the
lab.
1. Do not use conc. Acids as they are harmful.
2. Handle glass material with care.
3Never smell a gas directly.
2. Perform all the activities under the observation of teacher.
3. Keep all the chemicals away from the burner.
Metals and Non-metals
1.To study the lustre.




Take samples of iron, copper,aluminium and magnesium. Note the
appearance of each sample.
Clean the surface of each sample by rubbing them with sand paper and note
their appearance again.
We observe that the samples becomes shiny.
Metals in their pure state, have a shining surface. This property is called
metallic luster.
2.To show hardness  cutting of metals.




Take small pieces of iron,copper,aluminium and magnesium.
Try to cut these metals with a sharp knife and note your observation.
Hold a piece of sodium metal with a pair of tongs.
Put it on a watch glass and try to cut it with a knife.
We observe that metals are generally hard .The hardness varies from metal to metal.
3.To show malleability and ductility.



Take pieces of iron , zinc, lead and copper .
place any one metal on a block of iron and strike it four or five times with a
hammer.
Repeat with other metals.





Record the change in the shape of these metals.
We observe that some metals can be beaten into thin sheets. This property is
called malleability.
Now consider some metals such as iron, copper, aluminium, lead etc.
observe that which of the following metals are also available in the form of
wires.
The ability of metals to be drawn into thin wires is called ductility.
4.Conduction of heat and electricity.







Take an aluminium and copper wire .Clamp this wire on a stand
Fix a pin to the free end of the wire using wax.
Heat the wire with a spirit lamp, candle or a burner near the place where it is
clamped.
We observe that the wire get melted, this is because the metals are good
conducters of heat and have high melting points.
Now step up an electric circuit .
Place the metal to be tested in the circuit between the terminals.
We observe that the bulb glow.
5.Burning of magnesium ribbon.




Take a magnesium ribbon and some sulphur powder.
Burn the magnesium ribbon. Collect the ashes formed and dissolve them in
water.
Test the resultant solution with both red and blue litmus paper.
The product formed is basic .
6.Burning of sulphur powder and test the nature of oxideformed.
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Burn sulphur powder .Place the test tube over the burning sulphur to collect
the fumes produced.
Add some water to the above test tube and shake.
Test this solution with blue and red litmus paper.
The product formed is acidic.
7.To show the rusting of iron.
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Take three test tubes and place clean iron nails in each of them.
Label these test tubes (A), (B) and (C).Pour some water in test tube (A) and
cork it.
Pour distilled water in test tube (B), add about 1ml of oil and cork it .The oil
will float on water and prevent the air from dissolving in the water.
Put some anhydrous calcium chloride in test tube (C)and cork it. Anhydrous
calcium chloride will absorb the moisture.
We observe that the iron nails rust in test tube (A) but not in (B) and (C).
8. Flame test of metal salts.
Take samples of sodium chloride, potassium iodide, barium chloride or any other salt
from the science laboratory.
Take a small amount of a sample on a metal spatula heat directly on the flame.
Repeat with other samples . The samples impart colour to the flames.
It is observed that – (i) Sodium imparts a golden yellow colour to
theflame.
(ii) Potassium gives a crimson red colour to
the flame.
Students can heat more metal salts and note down the colour.
PHYSICS ACTIVITIES FOR CLASS X(SCIENCE)
Lesson- Electricity
Activity 1:- To find resistance R of a given wire
i)Connect the circuit as shown.
ii) Plug in the key A. As current starts flowing, take the readings of ammeter and
voltmeter
iii) Vary the position of rheostat terminal and read current and potential across the unknown
resistor R again
iv) Find the ratio V / I in each case. This is a constant ratio and is equal to value of R
Activity 2:- To prove the current carried by resistors connected in series is the same.
i)Connect the circuit as shown.
ii) Plug in the key. As soon as the current starts flowing in the circuit, the voltmeter V1, V2
and V3 shows deflection.
iii) The reading of all the voltmeters is found to be the same.
Activity 3:- To prove that potential across all resistors connected in parallel is the same.
i)Connect the circuit as shown in the figure
ii)Plug in the key. As soon as the current starts flowing in the circuit, the ammeters A1, A2 and A3
show deflection.
iii)Take reading of A1 for R1, A2 for R2 and A3 for R3
iv)Using Ohm’s law, find V1= (I1 R1), V2(I2 R2), AND V3(I3 R3) verify that V1 = V2 = V3
Activity 4:- Verification of Ohm’s Law
 Set up a circuit as shown in fig , consisting of a nichrome wire XY of length, say 0.5m, an
ammeter, a voltmeter and four cells of 1.5V each.(Nichrome is an alloy of nickel, chromium,
manganese, and iron metals)
 First use only one cell as the source in the circuit. Note the reading in the ammeter I , for the
current and reading of the voltmeter V for the potential difference across the nichrome wire
XY in the circuit. Tabulate them in the Table given.
 Next connect two cells in the circuit and note the respective readings of the ammeter and
voltmeter for the values of current through the nichrome wire and potential difference
across the nichrome wire.
 Repeat the above steps using three cells and then four cells in the circuit separately.
 Calculate the ratio of V to I for each pair of potential difference V and current I
Lesson – Magnetic effects of current
Activity1:- To draw magnetic field lines.
 Take a small compass and a bar magnet.
 Place the magnet on a sheet of white paper fixed on a drawing board, using some adhesive
material.
 Make the boundary of the magnet.
 Place the compass near the north pole of the magnet. The south pole of the needle points
towards the north pole of the magnet. The north pole of the compass is directed away from
the north pole of the magnet.
 Mark the position of two ends of the needle.
 Now move the needle to a new position such that its south pole occupies the position
previously occupied by its north pole.
 In this way, proceed step by step till you reach the south pole of the magnet.
 Join the points marked on the paper by a smooth curve. This curve represents a field line.
 Repeat the above procedure and draw as many lines as you can. You will get a pattern shown
in fig. These lines represent the magnetic field around the magnet. These are known as
magnetic field lines.
 Observe the deflection in the compass needle as you move it along a field line. The deflection
increases as the needle is moved towards the poles.
Activity 2:- To show that a current – carrying conductor in a magnetic field experience force.
 Take a small aluminium rod AB(of about 5cm). Using two connecting wires suspend it
horizontally from a stand, as shown in fig.
 Place a strong horse-shoe magnet in such a way that the rod lies between the two poles with
the magnetic field directed upwards. For this put the North Pole of the magnet vertically
below and south pole vertically above the aluminium rod.
 Connect the aluminium rod in series with a battery, a key and a rheostat.
 Now pass a current through the aluminium rod from end B to end A.
 It is observed that the rod is displayed towards the left.
 Reverse the direction of current flowing through the rod and observe the direction of its
displacement . It is now displayed towards the right.
 This shows that current carrying conductor experiences magnetic force and direction of this
force depend upon direction of current in the conductor.
Activity 3:- To make an electromagnets.
 A straight solenoid can be formed by taking a long cardboard or a thick paper tube and
then wrapping the tube by a large number of well-insulated turns of a copper wire.
Attach a hook to the solenoid and suspend it from a rigid support with the help of
approximate one metre long thread so that it can move freely.
 Allow the current to pass through the solenoid with the help of a battery. It is observed
that the solenoid comes to rest in a definite direction. Take a compass needle and
observe this direction. It is observed that the straight solenoid comes to rest in northsouth direction in the same way as a bar magnet does.
 The direction of the current in the solenoid determines the polarity of its ends. If the
current flows in the anticlockwise direction, then this end will be North Pole, and the
other end will be South Pole. If the current flows in the clockwise direction, then this end
will be South Pole, and other end will be North Pole.
Lesson- Light Reflection and Refraction
Activity1:- Refraction of light through a glass slab.
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Fix a sheet of white paper on a drawing board using drawing pins.
Place a rectangular glass slab over the sheet in the middle
Draw the outline of the slab with a pencil. Let us name the outline as ABCD.
Take four identical pins.
Fix two pins, say E and F, vertically such that the line joining the pins is inclined to the
edge AB.
Look for the images of the pins E and F through the opposite edge. Fix two other pins,
say G and H, such that these pins and the images of E and F lie on a straight line.
Remove the pins and the slab.
Join the positions of tip of the pins E and F and produce the line upto AB. Let EF meet AB
at O. Similarly, join the positions of tip of the pins G and H and produce it up to the edge
CD. Let HG meet CD at O’
Join O and O’. Also produce EF up to P, as shown by a dotted line in fig.
Activity 2:- To study the refraction of light through a triangular glass prism.
 Fix a sheet of white paper on a drawing board using drawing pins.
 Place a glass prism on it in such a way that it rests on its triangular base. Trace the outline of
the prism using a pencil.
 Draw a straight line PE inclined to one of the refracting surfaces, say AB, of the prism.
 Fix two pins, say at points P and Q on the line PE as shown in fig.
 Look for the images of the pins, fixed at P and Q through the other face AC.
 Fix two more pins at R and S such that the pins at R and S and images of P and Q lie in the
same straight line.
 Remove the pins and the glass prism.
 The line PE meets the boundary of the prism at point E. Similarly join and produce the points
R and S. Let these lines meet the boundary of the prism at E and F respectively. Join E and F.
 Draw perpendiculars to the refracting surfaces and AC of the prism at point E and F.
 Mark the angle of incidence (< i), the angle of refraction (<r) and angle of emergence <e.
Activity 3:- To determine the focal length of a concave mirror by obtaining the image of a distant
object.
 Fix the concave mirror on a holder in an upright and place it near an open window so that
adequate light can fall on it.
 Hold concave mirror in front of some distant objects like a tree, a pole etc.
 Try to get an image of distant object on the wall.
 Move the upright carrying concave mirror towards or away from the wall so that a sharp,
inverted and clear image of the distant object is formed on the wall.
 Measure the distance between concave mirror and the wall with the help of a metre scale.
This distance gives the rough focal length of concave mirror.
 Mount the concave mirror on the extreme side of the optical bench.
 Mount the two needles- object needle AB and the image Needle A’B’ on the optical bench
such that the tips of the two needles and the pole of the concave mirror are in same line
 Adjust one end of the knitting needle near the pole of concave mirror and the other end of
knitting needle is touched to the tip of the object needle AB.
 Note the distance between the concave mirror and the object needle AB. Let it be termed as
x.
 Measure the length of the knitting needle. Let it be y.
 The index correction for object distance comes out to be(x-y)
 Similarly, find the index correction for image distance by placing image needle and concave
mirror between two ends of knitting needle.
 If the distance measured between image needle and concave mirror is z, then the index
correction for image distance comes out to be(x-z)
 Now, place the object needle at a distance between f and 2f from the concave mirror.
 The image needle is placed just below the image beyond the centre of curvature C.
 Remove the parallax tip to tip between the image needle and the image of object needle.
 Note the positions of uprights of concave mirror P, object needle AB and image needle A’B’.
 The distance PB and PB’ on the optical bench gives the object distance u and the image
distance v.
 Repeat the above experiment thrice by placing object needle at different positions.
 Small piece of paper can be attached to the object needle so as to differentiate it from image
needle while removing the parallax.
 Record the observations in a tabular form.
Activity 4:- To determine the focal length of a convex lens by obtaining the image of a distant
object.
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Fix the convex lens in the holder in an upright.
Take the upright carrying convex lens near the wall of the laboratory.
Place the convex lens towards any distant objects like a tree, a pole etc.
Move the upright carrying convex lens, towards or away from the wall.
Focus a sharp, clear and inverted image of a distant object on the wall.
Measure the distance between the position of convex lens and the wall with the help of
metre scale. This gives rough focal length f of convex lens. Measure rough focal length twice.
Place the needle uprights on the optical bench with the lens upright in between.
Adjust the heights of object needle AB, image needle A’B’ in such a way that the centre of
the convex lens and the tips of the two needles are in one line.
Place the object needle AB between f and 2f.
Look for its real, inverted image(A’’B’’) from the other side of the convex lens.
Moving the image needle A’B’ and the other image (A’’B’’ )of object needle AB, remove
parallax between imageA’’B’’ and image needle A’B’.
 Note the positions of the object needleAB, convex lens C and the image needle A’B’.
 Measure the length of the knitting needle. Let it be x.
 Adjust one end of the knitting needle near the buldged part of the lens and the other end of
the knitting needle is touched to the tip of the object needle AB.
 Note the distance between the convex lens and the object needle AB. Let it be y.
 Adjust one end of the knitting needle near the buldged part of the other side of the lens and
the other end of the knitting needle is touched to the tip of the image needle A’B’.
 Note the distance between the convex lens and the image needle A’B’. Let it be z.
 Index correction for the object distance comes to be (x-y) and the index correction for the
image distance comes out to be (x-z)
 Apply the index corrections to object distance u and the image distance v.
 Record the observations in tabular form.
PHYSICS ACTIVITIES FOR CLASS X(SCIENCE)
Lesson- Electricity
Activity 1:- To find resistance R of a given wire
i)Connect the circuit as shown.
ii) Plug in the key A. As current starts flowing, take the readings of ammeter and
voltmeter
iii) Vary the position of rheostat terminal and read current and potential across the unknown
resistor R again
iv) Find the ratio V / I in each case. This is a constant ratio and is equal to value of R
Activity 2:- To prove the current carried by resistors connected in series is the same.
i)Connect the circuit as shown.
ii) Plug in the key. As soon as the current starts flowing in the circuit, the voltmeter V1, V2
and V3 shows deflection.
iii) The reading of all the voltmeters is found to be the same.
Activity 3:- To prove that potential across all resistors connected in parallel is the same.
i)Connect the circuit as shown in the figure
ii)Plug in the key. As soon as the current starts flowing in the circuit, the ammeters A1, A2 and A3
show deflection.
iii)Take reading of A1 for R1, A2 for R2 and A3 for R3
iv)Using Ohm’s law, find V1= (I1 R1), V2(I2 R2), AND V3(I3 R3) verify that V1 = V2 = V3
Activity 4:- Verification of Ohm’s Law
 Set up a circuit as shown in fig , consisting of a nichrome wire XY of length, say 0.5m, an
ammeter, a voltmeter and four cells of 1.5V each.(Nichrome is an alloy of nickel, chromium,
manganese, and iron metals)
 First use only one cell as the source in the circuit. Note the reading in the ammeter I , for the
current and reading of the voltmeter V for the potential difference across the nichrome wire
XY in the circuit. Tabulate them in the Table given.
 Next connect two cells in the circuit and note the respective readings of the ammeter and
voltmeter for the values of current through the nichrome wire and potential difference
across the nichrome wire.
 Repeat the above steps using three cells and then four cells in the circuit separately.
 Calculate the ratio of V to I for each pair of potential difference V and current I
Lesson – Magnetic effects of current
Activity1:- To draw magnetic field lines.
 Take a small compass and a bar magnet.
 Place the magnet on a sheet of white paper fixed on a drawing board, using some adhesive
material.
 Make the boundary of the magnet.
 Place the compass near the north pole of the magnet. The south pole of the needle points
towards the north pole of the magnet. The north pole of the compass is directed away from
the north pole of the magnet.
 Mark the position of two ends of the needle.
 Now move the needle to a new position such that its south pole occupies the position
previously occupied by its north pole.
 In this way, proceed step by step till you reach the south pole of the magnet.
 Join the points marked on the paper by a smooth curve. This curve represents a field line.
 Repeat the above procedure and draw as many lines as you can. You will get a pattern shown
in fig. These lines represent the magnetic field around the magnet. These are known as
magnetic field lines.
 Observe the deflection in the compass needle as you move it along a field line. The deflection
increases as the needle is moved towards the poles.
Activity 2:- To show that a current – carrying conductor in a magnetic field experience force.
 Take a small aluminium rod AB(of about 5cm). Using two connecting wires suspend it
horizontally from a stand, as shown in fig.
 Place a strong horse-shoe magnet in such a way that the rod lies between the two poles with
the magnetic field directed upwards. For this put the North Pole of the magnet vertically
below and south pole vertically above the aluminium rod.
 Connect the aluminium rod in series with a battery, a key and a rheostat.
 Now pass a current through the aluminium rod from end B to end A.
 It is observed that the rod is displayed towards the left.
 Reverse the direction of current flowing through the rod and observe the direction of its
displacement . It is now displayed towards the right.
 This shows that current carrying conductor experiences magnetic force and direction of this
force depend upon direction of current in the conductor.
Activity 3:- To make an electromagnets.
 A straight solenoid can be formed by taking a long cardboard or a thick paper tube and
then wrapping the tube by a large number of well-insulated turns of a copper wire.
Attach a hook to the solenoid and suspend it from a rigid support with the help of
approximate one metre long thread so that it can move freely.
 Allow the current to pass through the solenoid with the help of a battery. It is observed
that the solenoid comes to rest in a definite direction. Take a compass needle and
observe this direction. It is observed that the straight solenoid comes to rest in northsouth direction in the same way as a bar magnet does.
 The direction of the current in the solenoid determines the polarity of its ends. If the
current flows in the anticlockwise direction, then this end will be North Pole, and the
other end will be South Pole. If the current flows in the clockwise direction, then this end
will be South Pole, and other end will be North Pole.
Lesson- Light Reflection and Refraction
Activity1:- Refraction of light through a glass slab.
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
Fix a sheet of white paper on a drawing board using drawing pins.
Place a rectangular glass slab over the sheet in the middle
Draw the outline of the slab with a pencil. Let us name the outline as ABCD.
Take four identical pins.
Fix two pins, say E and F, vertically such that the line joining the pins is inclined to the
edge AB.
 Look for the images of the pins E and F through the opposite edge. Fix two other pins,
say G and H, such that these pins and the images of E and F lie on a straight line.
 Remove the pins and the slab.
 Join the positions of tip of the pins E and F and produce the line upto AB. Let EF meet AB
at O. Similarly, join the positions of tip of the pins G and H and produce it up to the edge
CD. Let HG meet CD at O’
 Join O and O’. Also produce EF up to P, as shown by a dotted line in fig.
Activity 2:- To study the refraction of light through a triangular glass prism.
 Fix a sheet of white paper on a drawing board using drawing pins.
 Place a glass prism on it in such a way that it rests on its triangular base. Trace the outline of
the prism using a pencil.
 Draw a straight line PE inclined to one of the refracting surfaces, say AB, of the prism.
 Fix two pins, say at points P and Q on the line PE as shown in fig.
 Look for the images of the pins, fixed at P and Q through the other face AC.
 Fix two more pins at R and S such that the pins at R and S and images of P and Q lie in the
same straight line.
 Remove the pins and the glass prism.
 The line PE meets the boundary of the prism at point E. Similarly join and produce the points
R and S. Let these lines meet the boundary of the prism at E and F respectively. Join E and F.
 Draw perpendiculars to the refracting surfaces and AC of the prism at point E and F.
 Mark the angle of incidence (< i), the angle of refraction (<r) and angle of emergence <e.
Activity 3:- To determine the focal length of a concave mirror by obtaining the image of a distant
object.
 Fix the concave mirror on a holder in an upright and place it near an open window so that
adequate light can fall on it.
 Hold concave mirror in front of some distant objects like a tree, a pole etc.
 Try to get an image of distant object on the wall.
 Move the upright carrying concave mirror towards or away from the wall so that a sharp,
inverted and clear image of the distant object is formed on the wall.
 Measure the distance between concave mirror and the wall with the help of a metre scale.
This distance gives the rough focal length of concave mirror.
 Mount the concave mirror on the extreme side of the optical bench.
 Mount the two needles- object needle AB and the image Needle A’B’ on the optical bench
such that the tips of the two needles and the pole of the concave mirror are in same line
 Adjust one end of the knitting needle near the pole of concave mirror and the other end of
knitting needle is touched to the tip of the object needle AB.
 Note the distance between the concave mirror and the object needle AB. Let it be termed as
x.
 Measure the length of the knitting needle. Let it be y.
 The index correction for object distance comes out to be(x-y)
 Similarly, find the index correction for image distance by placing image needle and concave
mirror between two ends of knitting needle.
 If the distance measured between image needle and concave mirror is z, then the index
correction for image distance comes out to be(x-z)
 Now, place the object needle at a distance between f and 2f from the concave mirror.
 The image needle is placed just below the image beyond the centre of curvature C.
 Remove the parallax tip to tip between the image needle and the image of object needle.
 Note the positions of uprights of concave mirror P, object needle AB and image needle A’B’.
 The distance PB and PB’ on the optical bench gives the object distance u and the image
distance v.
 Repeat the above experiment thrice by placing object needle at different positions.
 Small piece of paper can be attached to the object needle so as to differentiate it from image
needle while removing the parallax.
 Record the observations in a tabular form.
Activity 4:- To determine the focal length of a convex lens by obtaining the image of a distant
object.
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Fix the convex lens in the holder in an upright.
Take the upright carrying convex lens near the wall of the laboratory.
Place the convex lens towards any distant objects like a tree, a pole etc.
Move the upright carrying convex lens, towards or away from the wall.
Focus a sharp, clear and inverted image of a distant object on the wall.
Measure the distance between the position of convex lens and the wall with the help of
metre scale. This gives rough focal length f of convex lens. Measure rough focal length twice.
Place the needle uprights on the optical bench with the lens upright in between.
Adjust the heights of object needle AB, image needle A’B’ in such a way that the centre of
the convex lens and the tips of the two needles are in one line.
Place the object needle AB between f and 2f.
Look for its real, inverted image(A’’B’’) from the other side of the convex lens.
Moving the image needle A’B’ and the other image (A’’B’’ )of object needle AB, remove
parallax between imageA’’B’’ and image needle A’B’.
Note the positions of the object needleAB, convex lens C and the image needle A’B’.
Measure the length of the knitting needle. Let it be x.
 Adjust one end of the knitting needle near the buldged part of the lens and the other end of
the knitting needle is touched to the tip of the object needle AB.
 Note the distance between the convex lens and the object needle AB. Let it be y.
 Adjust one end of the knitting needle near the buldged part of the other side of the lens and
the other end of the knitting needle is touched to the tip of the image needle A’B’.
 Note the distance between the convex lens and the image needle A’B’. Let it be z.
 Index correction for the object distance comes to be (x-y) and the index correction for the
image distance comes out to be (x-z)
 Apply the index corrections to object distance u and the image distance v.
 Record the observations in tabular form.
CHEMICAL REACTIONS AND EQUATIONS
CHEMICAL REACTIONS AND EQUATIONS
(BALANCING OF EQUATIONS)
Chemical Equation
Chemical Equation represents a chemical reaction symbolically.
Mg
+
O2
MgO
(Reactants)
(Product)
Balanced Chemical Equation
A Chemical Equation is said to be balanced when the number of atoms of each
element remains the same before and after a Chemical Reaction.
LAW OF CONSERVATION OF MASS
Mass can neither be created nor be destroyed.
Chemical Reactions
Chemical Reactions involve the breaking and making of bonds between
atoms to produce new substances
Chemical Reactions – Types
Combination reaction.(synthesis reaction.)-Reaction in which
two or more reactants combine to form a single product.
Mg +O2
MgO
C + O2
CO2
2H2 +O2
2H2O
Decomposition reaction.- Reaction in which one reactant breaks
into two or more products.
CaCO3
heat
CaO + CO2
FeSO4
heat
Fe2O3 +SO2 +SO3
Displacement reaction.-reactions in which one metal displaces
the other metal from its compound in aqueous solution.
Fe + CuSO4
Pb + CuCl2
FeSO4 +Cu.
PbCl2 + Cu.
Double displacement reaction.- reactions in which two metals
displaces each other from their compounds in aqueous solution.
Na2SO4 +BaCl2
BaSO4 + 2NaCl.
NaCl +AgNO3
NaNO3 + AgCl
Oxidation and reduction reaction.
OXIDATION
2CuO + H2
2Cu + H2O
REDUCTION
CORROSION: An oxidation reaction which causes rusting of iron.
Definition: Attacking of metals by surrounding substances like
air,moisture,acids. For eg. Rusting of iron,a green coating on copper,
a black coating on silver.
Methods of preventing corrosion are paint, oiling. Greasing,
galvanizing, anodizing, electroplating and alloying
RANCIDITY: Changing of the taste and smell of fatty foods due to
oxidation of fats is called Rancidity.
Methods to prevent Rancidity:
Keep food in air tight containers.
Add antioxidants to the food.
Flush the packed foods with gases like nitrogen.
ACIDS, BASES AND SALTS
Acids
– Sour in taste
– Change the blue litmus to red
– eg.HydrochloricAcidHCl
Bases
– Bitter in taste
– Change red litmus to blue
eg. SodiumhydroxideNaOH
– SulphuricAcidH2SO4
PotassiumhydroxideKOH
– NitricAcidHNO3
CalciumhydroxideCa(OH)2
– AceticAcid CH3 COOH
– AmmoniumhydroxideNH4OH
Some Naturally occuring acids
Vinegar – AceticAcid
Orange – CitricAcid
Lemon – CitricAcid
Tamarind – TartaricAcid
Tomato – OxalicAcid
Sour milk (Curd) – LacticAcid
Ant and Nettle sting – MethanoicAcid
Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
Litmus solution – It is a natural indicator. It is a purple day extracted from
Lichens. Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
Chemical Properties of Acids and Bases
Acid + Metal Salt + Hydrogen
(Refer activity 2.3 on page No. 19 of NCERT Book)
2HCl + Zn ZnCl2 + H2
2HNO3 + Zn Zn (NO3)2 + H2
H2SO4 + Zn ZnSO4 + H2
2CH3COOH + Zn (CH3COO)2 Zn + H2
Base + Metal Salt + Hydrogen
NaOH + Zn Na2ZnO2 + H2
Action of Acids with metal Carbonates and metal bicarbonates
Metal Carbonate + Acid Salt + Carbondioxide + Water
Na2CO3(s)
+ 2HCl(aq) 2NaCl(aq) + H2O(l) + CO2(g)
Metal bicarbonate + Acid Salt + Carbondioxide + Water
NaHCO3 + HCl NaCl + CO2 + H2O
Lime water Test : On passing the CO2 gas evolved through lime water,
Ca(OH)2 (aq) + CO2(g) CaCO3(s) + H2O(l)
Lime water
White precipitate
On passing excess CO2 the following reaction takes place
CaCO3(s) + H2O(l) + CO2(g) Ca(HCO3)2 aq
Soluble in water
Neutralisation Reactions
Base + Acid Salt + Water
NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
Reactions of metal oxides with acids
Metal Oxide + Acid Salt + Water
CuO + HCl CuCl2 + H2O
Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base Salt + Water
Ca(OH)2 + CO2 CaCO3 + H2O
Refer activity 2.3 on page 22 of NCERT Book
– Glowing of bulb indicates that there is a flow of electric current through the
solution.
Alkalis
All bases do not dissolve in water. An alkali is a base that dissolves in water.
Common alkalis are
NaOH Sodium hydroxide
KOH Potassium hydroxide
Ca(OH)2 Calcium hydroxide
NH4OH :Ammonium hydroxide
Note : All alkalis are bases but all bases are not alkalis.
When an acid or a base is mixed with water they become dilute. This results
in the decrease in the concentration of H3O+ or OH– per unit volume in acids
and bases respectively.
strength of an Acid or Base
Strength of acids and bases depends on the no. of H+ions and OH–ions
produced respectively.
With the help of a universal indicator we can find the strength of an acid or
base. This indicator is called PH scale.
pH = Potenz in German means power.
This scale measures from 0 (very acidic) to 14 (very alkaline) 7 Neutral
(water in Neutral).
pH paper : Is a paper which is used for measuring PH.
Variation of PH
S. No. PH Value
Colour of the Paper
Nature of Solution H+ ion Conc. OH-ion
.
1.
0
Dark red
Highly acidic
very high
very low
2.
4
Orange or yellow
Acidic
high
low
3.
7:
Green
Neutral
Equal
Equal
4.
10
Bluish green or blue
5.
14
Dark blue or violet
– strongAcids give rise to more H+ions.
eg. HCl, H2SO4 and HNO3.
– Weak Acids give rise to less H+ ions
Alkaline
highly basic
eg. CH3 COOH, H2 CO3 (Carbonic acid)
– Strong Bases – Strong bases give rise to more OH– ions.
eg. NaOH, KOH, Ca(OH)2
– Weak Bases : give rise to less OH– ions.
eg. NH4OH
More about Salts
Salts and their derivation
S. No. Name of Salt Formula Derived from
1. Potassium Sulphate K2SO4 KOH H2SO4
2. SodiumSulphate Na2SO4 NaOH H2SO4
low
very low
high
very high
3. SodiumChloride NaCl NaOH HCl
4. AmmoniumChloride NH4Cl NH4OH HCl
Note : NaCl and Na2 SO4 belong to the family of sodium salts as they have
the same radicals. Similarly NaCl and KCl belong to the family of chloride
salts.
Importance of pH in our daily life
Importance of pH in our digestive system – pH level of our body regulates
our digestive system. In case of indigestion our stomach produces acid in a
very large quantity because of which we feel pain and irritation in our stomach.
To get relief from this pain antacids are used. These antacids neutralises the
excess acid and we get relief.
pH of Acid Rain : When pH of rain water is less than 5.6 it is called Acid
Rain.When this acidic rain flows into rivers these also get acidic, which causes
a threat to the survival of aquatic life.
pH of Soil : Plants require a specific range of pH for their healthy growth. If
pH of soil of any particular place is less or more than normal than the farmers
add suitable fertilizers to it.
Our body functions between the range of 7.0 to 7.8 living organisms can
survive only in the narrow range of pH change.
Tooth decay and pH : Bacteria present in the mouth produce acids by
degredation of sugar and food particles remaining in themouth.Using toothpaste
which is generally basic can neutralise the excess acid and prevent tooth
decay.
Bee sting or Nettle sting contains methanoic acid which causes pain and
irritation. When we use a weak base like baking soda on it we get relief.
Chemicals from Common Salt
– Sodium chloride is called as common salt used in our food. It is derived
from seawater.
– Rock Salt is the brown coloured large crystals. This s mined like coal.
– Common Salt is an important raw material for manymaterials of daily use
such as.
Sodiumhydroxide
Washing Soda
Bleaching Power.
SodiumHydroxide
Preparation : Prepared by the method called chlor-alkali
Called chlor-alkali because we get chlorine and a base in this.
2NaCl(aq) + 2H2O(l) 2NaOH(aq) + Cl2(g) + H2(g)
Bleaching Power
Preparation Ca(OH)2 +
calcium hydroxide
Cl2 CaOCl2 + H2O
chlorine
bleaching water
uses in textile, factories and laundry, used as disinfectant
Baking Soda
– Common name – Sodium Hydrogen Carbonate
Preparation NaCl + H2O + CO2 + NH3 NH4Cl + NaHCO3
On heating NaHCO3 produces :
NaHCO3 HeatNa2CO3 + H2O + CO2
CO2 produced causes dough to rise and make cakes, pastries spongy.
Uses : In household, ingredients of antacid
In making baking power
On heating baking powder produces
NaHCO3 + H+ CO2 + H2O + Sodium Salt of acid
Washing Soda
Preparation : Recrystallisation of sodium carbonate
Na2CO3 + 10H2O HeatNa2CO3. 10H2O
Uses
– Used in glass, soap and paper industry
– Cleaning agent for domestic purposes.
– Removal of hardness of water.
– Manufacturere of borax.
Water of crystallisation : Fixed no. of water molecules present in one formula
unit of a salt.
– On heating copper sulphate crystals water droplets appear, formula of
hydrated copper sulphate – CuSO4. 5H2O.
– gypsum also contains water of crystallisation.
– Formula of gypsum – CaSO4.2H2O
– On heating gypsum at 373k it becomes CaSO4.½H2O is plaster of
paris.
– Plaster of Paris is used as plaster for fractured bones.
– When plaster of Paris is mixed with water it changes to gypsum.
CaSO4.½ H2O + 1½ H2O CaSO4.2H2O
Uses of plaster of Paris :Making toys, decorativematerial and smooth surfaces.
METALS AND NON- METALS
HOW DO METALS AND NON- METALS REACT?
METAL
Let,s have a look at the electronic configuration of following elements.
Atom
atomic number
electronic configuration
Na
11
2,8, 1
Mg
12
2,8 , 2
Al
13
2, 8 ,3
Metals have 1 ,2 or 3 electrons in their outermost shell. They attain stable
configuration by losing their valence electrons and and become positive chargecation.
Now,let,s have a look at the Non- metals.
NON- METALS
ATOM
ATOMIC NUMBER
ELECTRONIC CONFIGURATION
N
7
2,5
O
8
2, 6
Cl
17
2 ,8, 7
Non metals have 5,6 or 7 electrons in their valence electrons. They attain stable
configuration by gaining electrons and become negative charge- anion.
Now , let,s see how metals and non metals react?
Sodium atom
Chlorine atom
-
+
_
Na+
Cl-
(Electrons=10
(electrons= 18
Protons= 11)
protons=
17)
NaCl
Sodium and Chloride, being oppositely charged, attract each other and are held by
strong electrostatic forces of attraction to exist as Sodium chloride.
NOTE: Sodium chloride exist as aggregates of oppositely charged ions.
FORMATION OF MAGNESIUM CHLORIDE
MgCl2
The Oxidation of Magnesium Metal
Recall from section 4.6, a magnesium atom loses its 2 outer-shell electron to
become a magnesium ion, (i.e. cation). The magnesium metal is said to be oxidized.
1. The Reduction of Chlorine Gas
Recall from section 4.7, chlorine is a diatomic element. The covalently bonded
Cl2 molecule gains two electrons to become two chloride ions, (i.e. anions).
Chlorine is said to be reduced.
2.
Combining the above oxidation and reduction processes, the overall effect is
the transfer of TWO electrons from magnesium to chlorine.
IONIC COMPOUNDS
The compounds formed by transfer of electrons from a metal to a non- metal.
PROPERTIES OF IONIC COMPOUNDS
1) PHYSICAL NATURE: Ionic compounds are solids and hard because of the strong
force of attraction between the positive and negative ions. These are Brittle.
2) MELTING AND BOILING POINTS: Ionic compounds have high melting and
Boiling points because a considerable amount of energy is required to break the
strong interionic attraction.
3) SOLUBILITY: Generally soluble in water and insoluble in solvents like
kerosene,petrol etc.
4) CONDUCTION OF ELECTRICITY: Conducts electricity in molten or aqueous state.
MOLTEN STATE: In molten state, the electrostatic force of attraction between the
oppositely charged ions are overcome by heat. Thus, the ions move freely and
conduct electricity.
AQUEOUS STATE: A solution of an ionic compound in water contains ions,which
move to the opposite electrodes when electricity is passed through the solution.
SOLID STATE: Ionic compounds do not conduct electricity in solid state because
movement of ions in solid is not possible due to their rigid structure.
Physical properties of non-metal
(1) Physical state: - Non Metals are either solid or gasses except Bromine.
(2) Non Metals are dull in lusture except iodine.
(3) Non Metals are soft except carbon.
(4) Non Metals are non-malleable and non-ductile.
(5) Non Metals are bad conductor of heat and electricity except graphite
which is good conductor of electricity.
Chemical properties of metal
(1) Reaction with air: - Metal + Oxygen
→
Metal Oxide
4Na + O2
→
2 Na2O
(2) Reaction with water: - Metal + Water→
Metal Oxide + Hydrogen
Metal Oxide + Water → Metal Hydroxide
2K + 2 H2O
→
2KOH + H2
(3) Reaction with Acid: - Metal + Acid → Salt + Hydrogen
2Na + 2HCL → 2NaCl + H2
(4) Reaction with salt: - More reactive metal displace less reactive method
from their salt solution.
Example: - Zn + CuSo4 → ZnSo4 + Cu
The arrangement of metals in the order of their decreasing reactivity is
known as activity series.
K
Most Reactive
Na
Ca
Mg
Al
Zn
Fe
Reactivity Decreases
Pb
H
Cu
Hg
Ag
Au
Least Reactive
METALLURGY
Various processes involved in the extraction of metal from their ores
and then refining them is known as metallurgy.
Extracting Metals low in the activity series: Metals lows in the activity series are very unreactive. Oxides of these
metals can be reduced to metals by heating alone. Eg.Cinnabar (HgS) is
an ore of Mercury.
2HgS + 3 O2
2HgO
→
→
2HgO + 2SO2
2Hg + O2
Extracting metal in the middle of the activity series: The metals are usually present as sulphide or carbonate in nature.
Sulphide ore are converted into oxides by heating strongly in the
presence of excess air. This process is known as roasting. The carbonate
ore are change into oxides by heating strongly in limited air. This process
is known as calcination.
Roasting: - 2ZnS + 3 O2
Calcination: - ZnCO3
ZnO + C
→
→
2ZnO + 2So2
→ ZnO + CO2
Zn + Co
Beside using carbon (coke) to reduce metal oxide to metals sometime
displacement reaction can also be used.
Displacement reactions arehighly exothermic eg. The reaction of iron(III)
oxide (Fe2O3) with alluminium is used to join railway tracks or cracked
machine parts. This reaction is known as thermit reaction.
Fe2O3 + 2Al
→
2Fe +Al2O3 + Heat
Extracting metals towards the top of the activity series: Metals high up in the activity series are very reactive. They can be
obtained from their compounds by heating with carbon. Eg. Na, Mg and
Ca are obtained by the electrolysis of their molten chloride. Metals are
deposit at the cathode were as chlorine is liberated at the anode.
At Cathode Na⁺
+ e⁻ → Na
At Anode 2Cl⁻
→ Cl2 + 2e⁻
CORROSION: - Combining of metal with oxygen in air in presence of
moisture is known as corrosion.
Methods of preventing corrosion are paint, oiling. Greasing, galvanizing,
anodizing, electroplating and alloying
CHAPTER – 6
LIFE PROCESSES
All living things perform certain life processes like growth, excretion, respiration,
circulation etc.All the processes like respiration, digestion, which together keep the living organisms
alive and perform the job of body maintenance are called life processes.Examples :Kinds of nutrition
in which in organicmaterials like CO2, water etc are utilized to prepare organic food by the process of
photosyntheses Eg. Green Plants Kinds of nutrition in which in organisms do not possess the ability to
synthesize their own food. They depend on autotrophs for their food supply directly or indirectly.eg.
Animals, Fung
Autotrophic Nutrition :The organisms which carry out autotrophic nutrition are called
autotrophs (greenplants)Autotrophic nutrition is fulfilled by the process by which autotrophs take in
CO2 and H2O and convert these into carlohydrates in the presence of chlorophyll, sunlight is called
PHOTOSYNTHESIS
Raw Materials for Photosynthesis :
Sunlight
nerals like Nitrogen
phosphorous etc are takenup by the roots from the soil. Site of Photosynthesis :Chloroplast in the
leaf. Chloroplast contain chlorophyll. (green pigment) Main Events of Photosynthesis :Absorption of
light energy by chlorophyll Conversion of light energy into chemical energy + splitting (breaking) of
water
into hydrogen and oxygen.Reduction of CO2 to carbohydrates.
STOMATA : Tiny pores present on the surface of the leaves
FUNCTIONS :
(i) Exchange of gases O2/CO2
(ii) Loses large amount of water [water vapour] during transpiration.
How do organisms obtain their food
Unicellular / single celled organism : food is taken up through entire surface.
Example : (i) Amoeba. (ii) Paramaecium
NUTRITION IN HUMAN BEINGS
The human digestive system comprises of alimentary canal and associated disgestive
Starch→Salivaryamylase[Saliva]Sugar Oesophagus Taking food from mouth to stomach by
glands secrete Gastric juice Small Intestinal Small Intestine → helps in absorption of food into the
of water. The rest of the material is removed from the body via theanus. (Egestion)
Respiration
Respiration involves
(i) Gaseous exchange : Intake of oxygen from the atmosphere and release of
CO2 → Breathing
(ii) Breakdown of simple food in order to release energy inside the cell →Cellular
Respiration
Breakdown of Glucose by various pathways
* Takes place in the presence of oxygen
* Occurs in mitochondria
* End products are CO2 and H2O
* More amount of energy is released
* Takes place in the absence of
oxygen
* Occurs in cytoplasm
* End products are alcohol or lactic
acid.
* Less amount of energy is released.
Human Respiratory System
Passage of air through the respiratory system.
Respiration in Plants :
Respiration in plants is simpler than the respiration in animals. Gaseous exchange
occur through
1. Stomata in leaves
2. Lenticels in stems
3. General surface of the roots.X-Science
The circulatory system in human beings consists of :
A Pumping Organ
Heart
Blood vessels
- Arteries & Veins
A circulatory medium
Blood & Lymph
Life Process (II)
Transportation and Excretion
– Human beings like other multicellular organism need regular supply of food,
oxygen etc., This function is performed by circulatory system or Transport
system.
– The circulatory system in human beings consists of :
Deoxygenate Blood (from body) VenaCava------ Right Atrium (Relaxed)----------Right
Atrium(contracts)----------- Right Ventricle (relaxed)-------------Body Partsvia AoRTA------------Right
ventricle contracts---------Lungs-------Left Ventricle (contracts)--------Left Ventricle (relaxed)------------Left Atrium(contracts)---------Left Atrium(relaxed)----------Oxygenated blood AORTA
Blood
(A fluid Connective Tissue)Solid Component,Blood Corpuscles,Liquid Component
-PLASMA
-R.B.C.s Blood
-Platelets
-W.B.C.
A yellow colour fluidcontain 90% water &10% Organic substances like
- Plasma Proteins viz.albumin, globulin inorganic-mineral ions Provide Body defence by engulfing the
germ cells & producing antibodies helps in Blood Clotting - carries respective gas (O , CO)
- contain Hb
impart red colourto me blood
- Lymph - a yellowish fluids escapes from the blood capillaries into the intercellular spaces
contain less proteins than blood. Lymph flows from the tissues to the heart assisting in
transportation and destroying germs.
Blood Vessels
Arteries & Veins
1. Carry Oxygenated blood from heart to body part except pulmonary Artery
2. Also called distributing Vessel
3. Thick and elastic
1. Carry deoxygenated blood from body parts to heart except pulmonary vein.
2. Also called collecting Vessel.
3. Thin and Less elastic.
Transportation in Plants
Xylem
1. Carries water & minerals from the roots to other part of the plant
2. No energy is used.
Phloem
1. C a r r i e s p r o d u c t o f photosynthesis from leaves to the other part of the plant.
2. Energy is used from ATP
Transpiration is the process of loss of water as vapour from aerial parts of the
plant.
Function :
1. Absorption and upward movement of water and minerals by creating
PULL.
2. helps in temperature regulation in Plant.
– Transport of food from leaves (food factory) to different part of the plant is
called Translocation.
EXCRETION
– The process of the removal of the harmful metabolic wastes from the body.
– Excretory system of human beings includes :
1) A pair of kidneys
ii) A Urinary Bladder
iii) A pair of Ureter
iv) A Urethera
– Urine produced in the kidneys passes through the ureters into the urinary
bladder where it is stored until it is released through the urethera.
– The purpose of making urine is to filter out waste product from the blood ie,
urea which is produced in the liver.
– Each kidney has large numbers of filtration units called nephrons.
– The Urine formation involves three steps
1. Glomerular Filtration : Nitrogenous wastes, glucose water, amino acid
filter from the blood into Bowman Capsule of the nephron.
2. Tubular reabsorption : Now, useful substances from the filtrate are
reabsorbed back by capillaries surrounding the nephron.
3. Secretion Extra, water, salts are secreted into the tubule which open up
into the collecting duct & then into the ureter.Haemodialysis : The process of purifying blood by an
artificial kidney. it is meant for Kidney failure patient.
Excretion in Plants
– Oxygen, CO2 & H2O
– Other wastes may be stored in leaves, bark etc. which fall off from the plant.
– Plants excrete some waste into the soil around them.
– Gums, Resin In old Xylem
– Some metabolic wastes in the form of crystals of Calcium oxalates in the
leaves of colocasia and stem of Zamikand.
CHAPTER – 7
Control and Coordination
Control and Coordination in Animals
It is brought about in all animals with the help of two main systems
a) Nervous System b) Endocrine System
Nervous System :
Functions
i) To receive the information from environment
ii) To receive the information from various
body parts. (Stimuli Response)
iii) To act accordingly through muscles and glands.
Stimulus : Any change in environment or within that bring about the reaction eg:
touching a hot plate.
Response : The reaction of our body to these changes. eg. withdrawal of our hand
How do we detect that we are touching a hot object?
Receptors : Are specialised tips of some nerve cells that detect the information
from the environment.
Receptors are Sense Organs Inner Ear Hearing/Balance of the body
Photo receptors Eyes Visual Stimulus
Olfactory Receptor (Nose ) Smell
Gustatory Receptor (Tongue) Taste
Skin Detection of Pain Touch Heat
Neuron (3 main parts)
Dendrite, Cell body and Axon
Synapse Information is acquired Information travels as an electrical impulse Part where electrical
signal
is converted into chemical message for onward transmission to next neuron by release of
neurotransmitters---Structure of Neuron:
Synapse : The point of contact between the terminal branches of axon of one
neuron with the dendrite of another neuron is called synapse.
Reflex Action
A quick, sudden, immediate response of the body to the certain stimuli that
involves Spinal cord. eg. (not brain) withdrawal of hand, knee jerk etc.
Reflex arc : The pathway through which impulses pass is called reflex arc.
Stimulus
Responses are of three main types
Voluntary : Controlled by fore brain eg. Talking, Writing
Involuntary : Controlled by mid and hind brain eg. Heart beat, vomiting, regulation of heartbeat
Reflex action : controlled by spinal cord eg. Withdrawl of hand on touching a hot object.
Human Nervous System
Sympathetic Nervous System -Arise from System the brain
Para Sympathetic Nervous-Arise from Spinal Card
Human Brain
Human brain has three major parts or regions
a) Forebrain b) Mid Brain c) Hind Brain
FOREBRAIN
Most complex/specialized part of the brain is CEREBRUM
FUNCTIONS :
1. Thinking part of the brain
2. Control the voluntary actions.
3. Store information (Memory)
4. Centre associated with HUNGER
5. Receives sensory impulses from various body parts and integrates it
Mid Brain :
HYPOTHALAMUS : Chemical co-ordination
PITUITARY GLAND : Secretes hormones
Hind Brain :
CEREBELLUM i) Controls posture and balance
ii) Control precision of voluntary actions
MEDULLA Controls involuntary actions
eg. blood pressure, salivation, vomiting
PONS Involuntary action, regulation of respiration
PROTECTION OF BRAIN AND SPINAL CORD
Brain : Brain is protected by a fluid filled balloon which acts as shock absorber and enclosed in
cranium (Brain Box)
Spinal Cord : Spinal Cord is enclosed in Vertebral column.
Coordination in Plants
Movement dependent on growth
Movement independent of growth [immediate response
to stimulus] eg. dropping of leaves of Touch-me-not plant on touching it
Movement in Plants
Tropic movements [directional movements
in response to stimulus]
Phototropism Movement towards light
Geotropism Movement towards gravity
Chemotropism Movement towards Chemicals/growth of pollen tube towards ovule
Hydrotropism Movement towards / water
Thigmotropism Mimosa (Touch me not)
Plant hormones :Are chemical compounds which help to coordinate growth, development and
responses to the environment.
Plant hormones : Main plant hormones are :
a) Auxin : [Synthesized at shoot tip]
Function : – Helps in growth
Phototropism : more growth of cells towards light.
b) Gibberellin : Helps in the growth of the stem
c) Cytokinins : Promotes cell division
d) Abscisic acid : Inhibits growth, cause witting of leaves.
(Stress hormone)
Hormones in Animals
Hormones : These are the chemical messengers secreted in very small amounts by
specialised tissues called ductless glands. They act on target tissues/organs usually
away from their source.
Endocrine System helps in control and coordination through chemical compounds
called HORMONES
Endocrine Gland
Location
1. Thyroxine
Functions
Thyroid Neck/ Regulation of metabolism
Throat of carbohydrates, fats
region and proteins.
2. Growth hormone
Pituitary Regulates growth development.
3. Adrenaline
Adrenal Above Regulation (increasing)
both of blood pressure, heart
kidneys heat, carbohydrate
metabolism (during emergency)
4. Testosterone
Testes Genital/ Changes associated
SEX in Males lower with puberty
Hormone abdomen (Sexual maturity)
estrogen Ovaries area
5. Insulin
Pancreas Below Reduces and regulates
stomach blood sugar level
IODISED SALTIS NECESSARYBECAUSE :
Iodine mineral is essential part of thyronine hormone so it is important that we
must consume iodised salt as in turn it is essential for thyroid gland as it controls
carbohydrate, proteins and fat metabolism for best balance of growth deficiency of
iodine might cause disease called goitre
Diabetes :
Cause : It is due to deficiency of Insulin hormone secreted by Pancreas that is
responsible to lower/control the blood sugar levels.
Treatment : Patients have to internally administer injections of insulin hormone
which helps in regulating blood-sugar level.
ELECTRICITY
Electric Current: The flow of electric charge is known as electric current. Electric
current is carried by moving electrons through a conductor.
By convention, electric current flows in opposite direction to the movement of
electrons.
Electric Circuit: Electric circuit is a continuous and closed path of electric current.
Expression of Electric Current: Electric current is denoted by letter ‘I’. Electric
current is expressed by the rate of flow of electric charges. Rate of flow means the
amount of charge flowing through a particular area in unit time.
If a net electric charge (Q) flows through a cross section of conductor in time t, then;
Where,I is electric current,Q is net charge and t is time in second.
SI unit of Electric Charge and Current:
SI unit of electric charge is coulomb (C).
One coulomb is nearly equal to 6 x 1018 electrons. SI unit of electric current is
ampere (A). Ampere is the flow of electric charges through a surface at the rate of
one coulomb per second. This means if 1 coulomb of electric charge flows through a
cross section for 1 second, it would be equal to 1 ampere.
Therefore; 1 A = 1 C/1 s
Small quantity of Electric Current: Small quantity of electric current is expressed in
milliampere and microampere. Milliampere is written as mA and microampere as μA
1mA (milliampere)= 10−3 A
1μA(microampere)=10−6 A
Ammeter: An apparatus to measure electric current in a circuit.
Electric Potential and Potential Difference
Electric Potential: The amount of electric potential energy at a point is called electric
potential.
Electric Potential difference: The difference in the amount of electric potential
energy between two points in an electric circuit is called ELECTRIC POTENTIAL
DIFFERENCE.
Electric potential difference is known as voltage, which is equal to the work done per
unit charge to move the charge between two points against static electric field.
Therefore;
Voltage or electric potential difference is denoted by ‘V’. Therefore;
Where, W = work done and Q = Charge
SI unit of electric potential difference (Voltage):
SI unit of electric potential difference is volt and denoted by ‘V’. This is named in
honour of Italian Physicist Alessandro Volta.
Since joule is the unit of work and coulomb is the unit of charge; 1 volt of electric
potential difference is equal to the 1 joule of work to be done to move a charge of 1
coulomb from one point to another in an electric circuit. Therefore,
Voltmeter: An apparatus to measure the potential difference or electric potential
difference between two points in an electric circuit.
Symbols used in a Circuit diagram
Ohm's Law
Ohm’s Law states that the potential difference between two points is directly
proportional to the electric current.
This means; potential difference V varies as electric current.
Or, V α I
Where R is constant for the given conductor at a given temperature and called
resistance. Resistance is the property of conductor which resists the flow of electric
current through it.
SI Unit of resistance is ohm. Ohm is denoted by Greek letter ‘Ω’.
1 ohm (Ω) of Resistance (R) is equal to the flow of 1 A of current through a conductor
between two points having potential difference equal to 1 V.
From the expression of Ohm’s Law it is obvious that electric current through a
resistor is inversely proportional to resistance. This means electric current will
decrease with increase in resistance and vice versa.
The graph of V (potential difference) versus I (electric current) is always a straight
line.
Resistance
Resistance is a property of conductor due to which it resists the flow of electric
current through it. Component that is used to resist the flow of electric current in a
circuit is called resistor.
In practical applications, resistors are used to increase or decrease the electric
current.
Variable Resistance: The component of an electric circuit which is used to regulate
the current; without changing the voltage from the source; is called variable
resistance.
Rheostat: This is a device which is used in a circuit to provide variable resistance.
Factors affecting Resistance in a Conductor:
Flow of electrons in a conductor is electric current. The particles of conductor create
hindrance to flow of electrons; because of attraction between them. This hindrance is
the cause of resistance in the flow of electricity.
Resistance in a conductor depends on nature, length and area of cross section of the
conductor.
Nature of material: Some materials create least hindrance and hence are called
good conductors. Silver is the best conductor of electricity. While some other
materials create more hindrance in the flow of electric current, i.e. flow of electrons
through them. Such materials are called bad conductors. Bad conductors are also
known as insulators. Hard plastic is the one of the best insulators of electricity.
Length of conductor: Resistance R is directly proportional to the length of the
conductor. This means, Resistance increases with increase in length of the
conductor. This is the cause that long electric wires create more resistance to the
electric current.
Thus, Resistance (R) ∝ length of conductor (l)
or R ∝ l --------(i)
Area of cross section: Resistance R is inversely proportional to the area of cross
section ( A) of the conductor. This means R will decrease with increase in the area of
conductor and vice versa. More area of conductor facilitates the flow of electric
current through more area and thus decreases the resistance. This is the cause that
thick copper wire creates less resistance to the electric current.
Thus, resistance ∝ 1/Area of cross section of conductor (A)
Where ρ (rho) is the proportionality constant. It is called the electrical resistivity of the
material of conductors.
From equation (iii)
The SI unit of resistivity: Since, the SI unit of R is Ω, SI unit of Area is m2 and SI
unit of length is m. Hence
Thus, SI unit of resistivity (ρ) is Ω m
Materials having resistivity in the range of 10−8 Ω m to 10−6 Ω m are considered as
very good conductors. Silver has resistivity equal to 1.60 X 10 −8 Ω m and copper has
resistivity equal to 1.62 X 10−8 Ω m.
Rubber and glass are very good insulators. They have resistivity in the order of
1012 Ω m to 1017 Ω m.
Resistivity of materials varies with temperature.
Resistance Of A System of Resistors:
Resistors are joined in two ways, i.e. in series and in parallel.
Resistors in Series: When resistors are joined from end to end, it is called in series.
In this case, the total resistance of the system is equal to the sum of the resistance of
all the resistors in the system.
Let total resistance = R
Resistance of resistors are R1, R2, R3, … Rn
Therefore, R = R1 + R2 + R3 + …………+ Rn
Resistors in parallel: When resistors are joined in parallel, the reciprocal of total resistance
of the system is equal to the sum of reciprocal of the resistance of resistors.
Let total resistance = R
Resistance of resistors are R1, R2, R3, … Rn
Heating Effect of Electric Current
When electric current is supplied to a purely resistive conductor, the energy of
electric current is dissipated entirely in the form of heat and as a result, resistor gets
heated. The heating of resistor because of dissipation of electrical energy is
commonly known as Heating Effect of Electric Current. Some examples are as
follows:
When electric energy is supplied to an electric bulb, the filament gets heated
because of which it gives light. The heating of electric bulb happens because of
heating effect of electric current.
Electric fuse: Electric fuse is used to protect the electric appliances from high voltage; if
any. Electric fuse is made of metal or alloy of metals, such as aluminium, copper, iron, lead,
etc. In the case of flow of higher voltage than specified, fuse wire melts and protects the
electric appliances.
Electric Power:
SI unit of electric power is watt (W).
1W = 1 volt x 1 ampere = 1V x 1A
1 kilo watt or 1kW = 1000 W
Consumption of electricity (electric energy) is generally measured in kilo watt.
Unit of electric energy is kilo watt hour (kWh)
1 kWh = 1000 watt X 1 hour = 1000 W x 3600 s
Or, 1kWh = 3.6 x 106 watt second = 3.6 x 106 J
Electricity At a Glance
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Electric Current: The flow of electric charge is known as electric current.
Electric current is carried by moving electrons through a conductor.
Electric current flows in the opposite direction of the movement of electrons.
Electric circuit: Electric circuit is a continuous and closed path of electric
current.
Electric current is denoted by letter ‘I’.
Electric current is expressed by the rate of flow of electric charges, i.e. amount
of charge flowing through a particular area in unit time.
Resistance in a conductor depends on nature, length and area of cross
section of the conductor.
Resistance increases with increase in length of the conductor. Resistance
decreases with increase in thickness of conductor.
Resistors in Series: When resistors are joined from end to end, it is called in
series. The total resistance of the system is equal to the sum of the resistance
of all the resistors connected in series in the system.
Resistors in parallel: When resistors are joined in parallel, the reciprocal of
total resistance of the system is equal to the sum of reciprocal of the
resistance of resistors.
When electric current is supplied to a purely resistive conductor, the energy of
electric current is dissipated entirely in the form of heat and as a result,
resistor gets heated. The heating of resistor because of dissipation of
electrical energy is commonly known as Heating Effect of Electric Current.
Joule’s Law of Heating: Heat produced in a resistor is directly proportional to
the square of current given to the resistor, directly proportional to the
resistance for a given current and directly proportional to the time for which the
current is flowing through the resistor.
SI unit of electric power is watt (W).
1W = 1 volt x 1 ampere = 1V x 1A
1 kilo watt or 1kW = 1000 W
1 kWh = 1000 watt x 1 hour = 1000 W x 3600 s ⇒ 1kWh = 3.6 x 106 watt
second = 3.6 x 106 J
MAGNETIC EFFECT OF CURRENT
CLASS 10
MAGNETIC FIELD AND FIELD LINES
A compass needle is, in fact, a small bar magnet. The ends of the compass needle point
approximately towards north and south directions.
The end pointing Towards north is called north seeking or north pole.
The other end that points towards south is called south seeking or south pole.
like poles repel, while unlike poles of magnets attract each other.
The region surrounding a magnet, in which the force of the magnet can be detected, is said
to have a magnetic field.
The iron filings arrange themselves in a pattern as shown Fig. The lines along which the iron
filings align themselves represent magnetic field lines.
Magnetic field is a quantity that has both direction and magnitude.
The direction of the magnetic field is taken to be the direction in which a north pole of the
compass needle moves inside it. Therefore it is taken by convention that the field lines
emerge from north pole and merge at the south pole (note the arrows marked on the field
lines) Inside the magnet, the direction of field lines is from its south pole to its north pole.
Thus the magnetic field lines are closed curves.
The relative strength of the magnetic field is shown by the degree of closeness of the field
lines.
The field is stronger, that is, the force acting on the pole of another magnet placed is greater
where the field lines are crowded.
No two field-lines are found to cross each other. If they did, it would mean that at the point
of intersection.
MAGNETIC FIELD DUE TO A CURRENT-CARRYING CONDUCTOR
an electric current through a metallic conductor produces a magnetic field around it.
Right Hand Thumb – Rule:-
Imagine that you are holding a current-carrying straight conductor in your right hand such
that the thumb points towards the direction of current. Then your fingers will wrap around
the conductor in the direction of the field lines of the magnetic field,
Magnetic Field due to a Current in a Solenoid:-
A coil of many circular turns of insulated copper wire wrapped closely in the shape of a
cylinder is called a solenoid.
The pattern of the magnetic field lines around a current-carrying solenoid is shown in Fig.
one end of the solenoid behaves as a magnetic north pole, while the other behaves as the
south pole. The field lines inside the solenoid are in the form of parallel straight lines.
the magnetic field is the same at all points inside the solenoid. That is, the field is
uniform inside the solenoid.
A strong magnetic field produced inside a solenoid can be used to magnetise a piece of
magnetic material, like soft iron, when placed inside the coil. The magnet so formed is called
an electromagnet.
Fleming’s left-hand rule:-
According to this rule, stretch the thumb, forefinger and middle finger of your left hand such
that they are mutually perpendicular(Fig. 13.13). If the first finger Points in the direction of
magnetic field and the second finger in the direction of current, then the thumb will point in
the direction of motion or the force acting on the conductor.
Devices that use current-carrying conductors and magnetic fields are electric motor, electric
generator, loudspeakers, microphones and measuring instruments.
An electric motor is a rotating device that converts electrical energy to mechanical energy.
Electric motor is used as an important component in electric fans, refrigerators, mixers,
washing machines, computers, MP3players etc.
ELECTROMAGNETIC INDUCTION:This was first studied by English physicist Michael Faraday. In 1831, Faraday made an
important breakthrough by discovering how a moving magnet can be used to generate
electric current.
The process, by which a changing magnetic field in a conductor induces a current in another
conductor ,is called electromagnetic induction.
Fleming’s right-hand rule
we can use a simple rule to know the direction of the induced current. Stretch the thumb,
forefinger and middle finger of right hand so that they are perpendicular to each other, as
shown in Fig. 13.18. If the forefinger indicates the direction of the magnetic field and the
thumb shows the direction of motion of conductor, then the middle finger will show the
direction of induced current. This simple rule is called Fleming’s right-hand rule.
DOMESTIC ELECTRIC CIRCUITSIn our homes, we receive supply of electric power through a main supply (also called mains),
either supported through overhead electric poles or by underground cables. One of the
wires in this supply, usually with red insulation cover, is called live wire (or positive). Another
wire, with black insulation, is called neutral wire (or negative). In our country, the potential
difference between the two
is 220 V.
Electric fuse is an important component of all domestic circuits.
A fuse in a circuit prevents damage to the appliances and the circuit due to overloading.
Overloading can occur when the live wire and the neutral wire come into direct contact.
TERM II- SCIENCE
CLASS X
EASY AND SCORING AREAS
Sr
.
n
o.
1
Name of
the
chapter
Topics
Carbon
1.Versatile
and its
nature
compound
2.Isomerism
Contents
CATENATION: The unique ability of carbon to bond
with other atoms of carbon, giving rise to large
molecules,
TETRAVALENCY: Carbon has valency four so it is
capable of bonding with four other atoms of carbon or
other atoms of monovalent element.
Compounds with same molecular formula but
different structures are called STRUCTURAL
ISOMERS.
Isomers of butane,
pentane,
hexane ,
3.Functional
groups
Benzene:
FUNCTIONAL GROUPS
NAME
ENDING
1) ALCOHOL
2) ALDEHYDE
3) ACID
4) KETONE
FUNCTIONAL
GROUP
|
—C—O—H
|
H
|
—C=O
O
||
—C—O—H
O
||
R—C—R
-ol
al
-oic acid
-one
covalent bond: 1) single covalent bond
2) double covalent bond
3) triple covalent bond
2.
Periodic
classificati
on of
elements
1.Mendeleev’ Meritss periodic
1. Systematic arrangements of 66 elements in groups
table
and periods.
2. Corrected doubtful masses of some elements like
Be,Pd,Pt etc.
3. Predicted properties of elements which were not
discovered -like scandium , gallium , germanium ,
which were correct and left gaps for them.
demerits-
1. Controversial position of hydrogen.
2. Position of isotopes was not correct.
3. Two similar elements like Cu & Hg were grouped
differently.
4. Co with higher atomic no. was placed before lower
atomic no. Ni which was contradicting arrangement of
element in increasing atomic no.
5. Did not provide space for noble gases which were
discovered later.
6. No space left for isotopes.
2.modern
periodic
table
Properties of elements are a periodic function of
their atomic number.”
properties of elements in groups
Group
1.
Atomic radius increases down the group because
number of shells increase.
2. Elements have same valence electrons.
GROUP 1
H (1) 1
Li(3) 2 1
Na(11)2 8 1
K( 19) 2 8 8 1
3. Metallic properties increase because number of
shells increases so, effective nuclear charge decreases.
Properties of elements in periods
Atomic radius decreases in moving from left to
Right because of increase in nuclear charge
Which tends to pull the electrons closer to the
Nucleus.
2. Valence electrons increases as atomic number
Increases.
PERIOD2;
Li
Be B C
N
O F
Ne
3
4
5 6
7
8 9
10
2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8
3.Metallic properties decrease because effective
nuclear charge increases.
Periodicity: Repetition of similar properties having
elements after certain interval of time.
CAUSE:Due to presence of same number of valence
electrons.
Note: metal oxides are basic in nature.
Non-metal oxide are acidic in nature.
3.
How do
organisms
reproduce
1.Asexual
Definition and diagram of types of fission ,
reproduction In binary fission; the parent organism splits to form
two new organisms.
1. Amoeba divides after it has grown to certain
size
2. Pseudopodia are pulled in and nucleus divide
3. The cell body begin to divide when nucleus has
split
4. Two daughter amoebae formed.
Multiple Fission means division of the parent
body into a number of daughter organisms.
Budding: In budding the new individual arises as
an outgrowth(bud) from the parent . In can be seen
in lower organisms like
a) HYDRA
b) YEAST
vegetative propagation
In vegetative propagation new plants are obtained
from the parts of old plants (like stems, roots and
leaves) without the help of any reproductive organ.
2.Parts of
flower

Pollination is the transfer of pollen grains from
the anther of stamen to stigma of carpel is called
3.pollination
pollination.
SELF POLLINATION: When pollen grains from the
anther of flower are transferred to stigma of same
flower it is called SELF POLLINATION.
2.CROSS POLLINATION: When the pollen grains from
anther of a flower on one plant are transferred to
stigma of flower on another plant is called CROSS
POLLINATION.
4.fertilizatio
n
5. Female
reproductive
system in
humans
6.Methods to
control
population
4.
Heredity
and
evolution
1.heredity
Barrier methods ,
Chemical method
Surgical method
The transfer of characters from parents to their
offspring
2. sex
determinatio
n
5.
Light
reflection
and
3.Evidences
of evolution
Homologous organs: organs having same structure
but different functions. Examples forelimbs of man,
dog, frog.
Analogous organs: organs having same functions but
different structure in different animals. Examples ,
wings of butterfly and wings of bat.
Vestigeal organs: ( in humans)ear muscles, tail bone,
nictitating membrane, appendix.
Fossils: Preserved traces (impressions and remains)
of living organisms 0f the past.
1.Laws of
reflection
1. The angle of incidence is always equal to angle of
reflection
2. The incident ray, the normal and the reflected ray at
refraction
the point of incidence all lies in the same plane.
2.Image
formation
CONCAVE MIRROR
CONVEX MIRROR
CONVEX LENS
CONCAVE LENS
4.Refraction
through
glass slab
5.Power of
lens
P = 1/f(in m) or P = 100/f(in cm)
S.I unit = D( diopter)
6.
Human
eye and
colourful
world
1.Human Eye
2.Defects of
vision
Myopia
hypermetropia
3.Dispersion
4.Rainbow
formation
7.
Our
Environm
ent
1.biodegrada Biodegradable waste: It is a type of waste, originating
ble and non- from plant or animal sources, which may be degraded
biodegradabl by other living organisms.
e substances
Non-biodegradable: Waste that cannot be broken
down by other living organisms is called nonbiodegradable.
2.food chain
and food
web
3.ozone
Food chain
food web
Formation:
Decomposer
s
(CFC)
compounds,
commonly
called
Chlorofluorocarbon
These
compounds
are
transported into the stratosphere after being emitted
at the surface.
EFFECTS OF OZONE DEPLETION
5. Trophic
level
skin cancer, cataracts, damage to plants, and
reduction of plankton populations in the ocean's
photic zone may result from the increased UV
exposure due to ozone depletion.
Decomposers ( Bacteria and fungi) are
components of the nutrient cycle.
vital
1) Decomposers break down dead plant and
animal matter, so the nutrients contained
within them can be reused.
2) They act as a cleansing agent of the
environment.
Each step or level of the food chain forms a TROPHIC
LEVEL.
TEN PERCENT LAW:
According to the law, during the transfer of organic
food from one trophic level to the next, only about ten
percent of the organic matter is stored as flesh. The
remaining is lost during transfer or broken down in
respiration.
.
8.
Manageme 1.3 R’s
Reduce, reuse and recycle
nt of
Natural
2.Sustainable The protection of environment and avoiding
resources development depletion of natural resources.
3.conservati
on of forest
Needs: 1. Hot spot of biodiversity
2. transpiration of plants & helps in raining
3. Provide timber, medicines, oils spices, raisins
and gums.
ELECTRICITY
GIST OF THE LESSON
1. Positive and negative charges: The charge acquired by a glass rod when rubbed with silk
is
called positive charge and the charge acquired by an ebonite rod when rubbed with wool is
called negative charge.
2. Coulomb: It is the S.I. unit of charge. One coulomb is defined as that amount of charge
which
repels an equal and similar charge with a force of 9 x 109 N when placed in vacuum at a
distance of 1 meter from it. Charge on an electron = -1.6 x 10-19coulomb.
3. Static and current electricities: Static electricity deals with the electric charges at rest
while
the current electricity deals with the electric charges in motion.
4. Conductor: A substance which allows passage of electric charges through it easily is
called a
‗conductor‘. A conductor offers very low resistance to the flow of current. For example
copper,
silver, aluminium etc.
5. Insulator: A substance that has infinitely high resistance does not allow electric current to
flow through it. It is called an insulator‘. For example rubber, glass, plastic, ebonite etc.
6. Electric current: The flow of electric charges across a cross-section of a conductor
constitutes
an electric current. It is defined as the rate of flow of the electric charge through any section
of
a conductor. Electric current = Charge/Time
I = Q/t
Electric current is a scalar quantity.
Charge: Number of electrons flowing
Q = ne
n = 1, 2, 3,……….
e = charge on electron = 1.6*10-19 C
7. Ampere: It is the S.I. unit of current. If one coulomb of charge flows through any section
of a
conductor in one second, then current through it is said to be one ampere.
1 ampere = 1 coulomb/1 second
1 A = 1C/1s = 1Cs-1
1 milliampere = 1 mA = 10-3 A
1 microampere = 1μA = 10-6 A
8. Electric circuit: The closed path along which electric current flows is called an electric
circuit‘.
9. Conventional current: Conventionally, the direction of motion of positive charges is taken
as
the direction of current. The direction of conventional current is opposite to that of the
negatively charged electrons.
10. Electric field: It is the region around a charged body within which its influence can be
experienced.
11. Electrostatic potential: Electrostatic potential at any point in an electric field is defined
as the amount of work done in bringing a unit positive charge from infinity to that point. Its
unit is
volt. Positive charges move from higher to lower potential regions. Electrons, being
negatively
charged, move from lower to higher potential regions.
12. Potential difference between two points: The Potential difference between two points in
an
electric field is the amount of work done in bringing a unit positive charge from one to
another.
Potential difference = Work done/Charge
V = W/Q
13. One volt potential difference: The Potential difference between two points in an electric
field is said to one volt if one joule of work has to be done in bringing a positive charge of
one
coulomb from one point to another.
1 volt = 1 joule/1coulomb
1 V = 1J/1C
14. Galvanometer: It is device to detect current in an electric circuit.
15. Ammeter: It is device to measure current in a circuit. It is always connected in series in a
circuit.
16. Voltmeter: It is a device to measure potential difference. It is always connected in parallel
to
the component across which the potential difference is to be measured.
17. Ohm’s law: This law states that the current passing through a conductor is directly
proportional to the potential difference cross its ends, provided the physical conditions like
temperature, density etc. remains unchanged.
VαI
V = RI
The proportionality constant R is called resistance of conductor.
18. Resistance: It is a property of a conductor by virtue of which it opposes the flow of
current
through it. It is equal to the ratio of the potential difference applied across its ends and the
current flowing through it.
Resistance = Potential difference/Current
R = V/I
19. Ohm: It is the S.I. unit of resistance. A conductor has a resistance of one ohm if a current
of
one ampere flows through it on applying a potential difference of one volt across its ends.
1 ohm = 1 volt/1 ampere
1Ω = 1V/1A
20. Factors on which resistance of a conductor depends: The resistance R of a conductor
depends
i) Directly on its length L i.e. R α L.
ii) inversely on its area of cross-section A i.e. R α 1/A
iii) on the nature of material of the conductor on.
On combining the above factors, we get
R α L/A
R = ρ * L/A
The proportionality constant ρ is called resistivity of conductor.
21. Resistivity: It is defined as the resistance offered by a cube of a material of side 1 m when
current flows perpendicular to its opposite faces. Its S.I. unit is ohm-meter (Ωm).
Resistivity, ρ = RA/L
22. Equivalent resistance: If a single resistance can replace the combination of resistances in
such a manner that the current in the circuit remains unchanged, then that single resistance is
called the equivalent resistance.
23. Laws of resistances in series:
i) Current through each resistance is same.
ii) Total voltage across the combination = Sum of the voltage drops.
V= V1 + V2 + V3
iii) Voltage drops across any resistor is proportional to its resistance.
V1 = IR1, V2 = IR2, V3 = IR3
iv) Equivalent resistance = Sum of the individual resistances.
Rs = R1 + R2 + R3
v) Equivalent resistance is larger than the largest individual resistance.
24. Laws of resistances in parallel:
i) Voltage across each resistance is same and is equal to the applied voltage.
ii) Total current = Sum of the currents through the individual resistances.
I = I1 + I2 + I3
iii) Currents through various resistances are inversely proportional to the individual
resistances.
I1 = V/R1, I2 = V/R2, I3 = V/R3
iv) Reciprocal of equivalent resistance = Sum of reciprocals of individual resistances.
1/Rp = 1/R1 + 1/R2 + 1/R3
v) Equivalent resistance is less than the smallest individual resistance.
25. Joule’s law of heating: It states that the heat produced in a conductor is directly
proportional
to (i) the square of the current I through it (ii) proportional to its resistances R and
(iii) the time t for which current is passed. Mathematically, it can be expressed as
H = I2Rt joule = I2Rt/4.18 cal
or
H = VIt joule = VIt/4.18cal
26. Electric energy: It is the total work done in maintaining an electric current in an electric
circuit for given time.
Electric energy,
W = VIt = I2Rt joule
27. Electrical power: Electrical power is the rate at which electric energy is consumed by an
appliance.
P = W/t = VI = I2R = V2/R
28. Watt: It is the S.I. unit of power. The power of an appliance is 1 watt if one ampere of
current
flows through it on applying a potential differences of 1 volt across its ends.
1 watt = 1 joule/1 second =1 volt x 1 ampere
1 W = 1 Js-1 = 1 VA
1 kilowatt = 1000 W
29. Kilowatt hour: It is the commercial unit of electrical energy. One kilowatt hour is the
electric
energy consumed by an appliance of 1000 watts when used for one hour.
1 kilowatt hour (kWh) = 3.6 x 106 J
Magic map
ORAL QUESTIONS
1. Which unit is equivalent of joule / coulomb?
2. How does the resistance of a wire depend on its length?
3. How does the resistance of a wire depend on its area of cross – section?
4. When are resistors said to be connected in series?
5. When are resistors said to be connected in parallel?
6. Why is tungsten suitable for making the filament of a bulb?
7. Why is tungsten not used as a fuse wire?
8. Alloys are preferred over metals for making the heating elements of heaters. Why?
9. How is the direction of electric current related to the direction of flow of electrons in
a wire?
10. Should the heating element of an electric iron be made of iron, silver or nichrome
wire?
MAGNETIC EFFECTS OF ELECTRIC
CURRENT
KEY CONCEPTS & GIST OF THE LESSON
Magnet: (i) is an object that attracts objects made of iron, cobalt & nickel.
(ii) Comes to rest in North-South direction, when suspended freely.
Magnets are used: (i) In radio & stereo speakers, (ii) In refrigerator doors, (iii) on audio
&
video cassettes players, (iv) On hard discs & floppies of computers & (v) in children‘s toys.
Magnetic field: The area around a magnet where a magnetic force is experienced is
called a
magnetic field. It is a quantity that has both direction & magnitude.
Magnetic field lines: Magnetic field is represented by field lines. They are lines drawn in
a
Magnetic field along which a North magnetic pole moves. Magnetic field lines are called as
Magnetic lines of force.
Properties of Magnetic field lines:
(i) They do not intersect each other.
(ii) It is taken by convention that magnetic field lines emerge from
North pole and merge at the South pole. Inside the magnet, their
direction is from South pole to North pole. Therefore magnetic field
lines are closed curves.
Magnetic field lines due to a current through a straight conductor (wire)- consist of series
of
concentric circles whose direction is given by the Right hand thumb rule.
Right hand thumb rule: If a current carrying straight conductor is held in your right hand
such that the thumb points towards the direction of current, then the wrapped fingers show the
direction of magnetic field lines.
Magnetic field lines due to a current through a circular loop
The strength of the magnetic field at he centre of the loop(coil)depends on:
(i) The radius of the coil- The strength of the magnetic field is inversely
proportional to the radius of the coil. If the radius increases, the
magnetic strength at the centre decreases.
(ii) The number of turns in the coil: As the number of turns in the coil
increase, the magnetic strength at the centre increases, because the
current in each circular turn is having the same direction, thus the
field due to each turn adds up.
(iii) The strength of the current flowing in the coil: as the strength of the
current increases, the strength of thee magnetic fields also increases.
Solenoid:
(i) A coil of many turns of insulated copper wire wrapped in the shape of a cylinder is
called
a Solenoid.
(ii) Magnetic field produced by a Solenoid is similar to a bar magnet.
(iii) The strength of magnetic field is proportional to the number of turns & magnitude of
current.
Electromagnet: An electromagnet consists of a long coil of insulated copper wire
wrapped on a soft iron core.
.
Fleming‘s Left hand rule: Stretch the thumb, forefinger and middle finger of left hand
such
that they are mutually perpendicular. Forefinger points in the direction of magnetic field and
centre finger in the direction of current, then the thumb gives the direction of force acting on
the conductor.
Electric motor: A device that converts electric energy to mechanical energy.
Principle of Electric motor: When a rectangular coil is placed in a magnetic field and a
current is passed through it, force acts on the coil, which rotates it continuously. With the
rotation of the coil, the shaft attached to it also rotates.
Electromagnetic induction: Electricity production as a result of magnetism (induced
current)
is called Electromagnetic induction.
Fleming‘s Right hand rule: gives the direction of induced current.
Stretch the thumb, forefinger and middle finger of right hand such that they are mutually
perpendicular. Forefinger points in the direction of magnetic field and centre finger in the
direction of induced current, then the thumb gives the direction of motion of the conductor.
Electric generator: A devise that converts mechanical energy to electric energy.
Electric generator is of two types- (i) A.C generator (ii) D. C generator
Principle of Electric generator: Electromagnetic induction
Domestic electric circuits)
We receive electric supply through mains supported through the poles or cables. In our
houses
we receive AC electric power of 220V with a frequency of 50Hz.
The 3 wires are as follows- (i) Live wire- (Red insulated, Positive)
(ii) Neutral wire- (Black insulated, Negative)
(iii) Earth wire- (Green insulated) for safety measure to ensure
that any leakage of current to a metallic body does not give
any serious shock to a user.
Short circuit: is caused by touching of live wires and neutral wire
Fuse: is a protective device used for protecting the circuits from short circuiting and over
loading
Important diagrams1. Magnetic field lines around a bar magnet.
2. Right hand thumb rule
3. Magnetic field lines through and around a current carrying solenoid.
4. An electromagnet.
5. A simple electric motor
6. Electric generator
Important activities1. Magnetic field lines around a bar magnet
2. Direction of electric current in a simple electric circuit.
3. Direction of Magnetic field lines depends on the direction of electric current.
MAGIC MAP
ORAL QUESTIONS
1. What important observation did Oersted make in his experiments with current carrying
conductors?
2. How can you locate a current – carrying wire concealed in a wall?
3. A freely suspended magnet always points along north – south direction. Why?
4. What type of core should be used inside a solenoid to make an electromagnet?
5. Name the SI unit of magnetic field.
6. What is the principle of an electric motor?
7. A generator converts energy from one form to another. What is this energy conversion?
8. Which wire (live, neutral or earth) goes through the switch?
9. Are different appliances connected in series or parallel in a house?
10. What is the colour convention for live, neutral and earth wires?
SOURCES OF ENERGY
KEY CONCEPTS & GIST OF THE LESSON
Characteristics of a good fuel:
1) High calorific value
2 Less smoke
3) Less residue after burning
4) Easy availability
5) Inexpensive
6) Easy to store and transport
Fossil fuels: were formed millions of years ago, when plants and animal remains got
buried
under the earth and were subjected to high temperature and pressure conditions. E.g.: Coal,
Petroleum, etc.
These fossil fuels are non renewable sources of energy and cause environmental problems due
to pollution.
Thermal power plants:
(i) Use coal, petroleum and natural gas to produce thermal electricity.
(ii) Electricity transmission is very efficient.
(iii) The steam produced by burning the fossil fuels runs the turbine to produce electricity
Hydro power plant:
(i) It is the most conventional renewable energy source obtained from water falling from a
great height.
(ii) It is clean & non polluting source of energy.
(iii) Dams are constructed to collect water flowing in high altitude rivers. The stored water
has a lot of potential energy.
(iv) When water is allowed to fall from a height, potential energy changes to kinetic energy,
which rotates the turbines to produce electricity.
Disadvantages of Hydro power plant:
(i) Highly expensive to construct.
(ii) Dams cannot be constructed on all river sites.
(iii) Large areas o human habitation and agricultural fields get submerged.
(iv) People face social and environmental problems.
Non conventional sources:
(1) Bio mass:
o It is the source of the conventionally used fuels that are used in our
country. E.g.: Cow dung cakes, fire-wood, coal, charcoal
o Bio gas: It is a mixture of gases produced during decomposition of bio
mass in the absence of Oxygen. (Anaerobic Respiration). Methane is the
major component of bio gas.
o Bio gas plants: Animal dung, sewage, crop residues, vegetable wastes,
poultry droppings, etc. are used to produce Bio gas in Bio gas plants.
(2) Wind energy:
o It can be converted into mechanical and electrical energy.
o Kinetic energy of the wind is used in running of wind mills, which are used
to lift water, grind grains, etc.
o Wind millo Advantages: (i) Eco friendly (ii) Renewable
o Disadvantages: (i) Wind speed not uniform always.
(ii) Needs a large area to erect series of wind mills.
(iii) Big amount of investment is needed.
(iv) Out put is less as compared to investment
(3) Solar energy:
o Solar radiations can be converted electricity through solar cells
(photovoltaic cells).
o Photovoltaic cells convert solar radiations directly into electricity through
silicon solar cells.
o Solar cells arrange on a large flat sheets form a solar panel.
o Solar cookers are painted black from outside and a large glass plate to trap
solar radiations by green house effect.
o Advantages of Solar cookers:
(i) Eco friendly
(ii) Renewable
(iii) Used in rural areas.
(iv) Retains all the nutrients in food due to slow cooking.
o Disadvantages of solar cooker:
(i) Silicon cells are expensive.
(ii) Solar radiations are not uniform over earth‘s surface.
(iii) Cannot be used at night or on cloudy days.
(iv) Cannot be used to make chapattis for frying as these
require a temperature of 1400C or more.
(Maximum temperature of 1000C only can be
achieved in a solar cooker)
o Other solar devices- Solar water heater, Solar furnace
(4) Geo thermal energy:
(i) Energy harnessed from the heat of the sun is called Geo thermal energy.
(ii) Magma is formed when this heat melts the rocks. The molten rocks and hot
gases are called magma
(iii) The magma gets collected at some depths below the earth‘s surfaces. These
places are called ‗Hot spots‖
(iv) When underground water comes in contact these hot spots, it changes into
steam, which can be used to generate electricity.
o Advantages of Geo thermal energy:
(i) Renewable
(ii) Inexpensive
o Disadvantages of Geo thermal energy:
(i) Only few sites available for harnessing energy.
(ii) Expensive
(5) Nuclear energy:
(i) Energy released when some changes take place in the nucleus of the atom of a
substance, is called Nuclear energy.
(ii) It is used for heat generation, fuel for marine vessels.
o Advantages of Nuclear energy:
(i) Alternative source of energy due to depletion of fossil fuels.
(ii) From a small amount of fuel, a large amount of energy is released.
o Disadvantages of Nuclear energy:
(i) Risk of nuclear waste leakage
(ii) High cost of setting up of nuclear plant
(iii) Pollution of environment.
(6) Energy from the sea(A) Tidal energy: Locations in India – Gulf of Kutch, Gujrat & W. Bengal
(i) Depends upon harnessing the rise and fall of sea level due to tidal action.
(ii) Dams are constructed across a narrow part of sea and turbine converts tidal
energy into electrical energy.
Disadvantages: Uniform tidal action is not seen
(B) Wave energy:
(i) Kinetic energy of the waves of sea are used to rotate turbines..
(ii) These turbines generate electrical energy
Important diagrams1. Hydro power plant
2. Bio gas plant
3. A wind mill
4. A solar cooker
MAGIC MAP
ORAL QUESTIONS (CONVERSATION TYPE)
1. a) What is a good source of energy?
b) Name one good source of energy.
c) It is a renewable source of energy?
d) Is it conventional or non – conventional source of energy?
e) What other name is give to it?
f) What is a fossil fuel?
g) Name any other two fossil fuels.
2. a) Which is the ultimate source of all forms of energy?
b) Can you explain?
c) Name some renewable source of energy arising due to sun.
d) Name some non – renewable source of energy arising due to sun.
e) Why is the energy contained in fossil fuels considered due to sun‘s energy?
f) Name any source of energy not influenced by sun‘s energy.
3. a) What is the principle of nuclear energy?
b) What are the kinds of nuclear reaction?
c) Which of these can be used for destructive purposes?
d) Which of these can be used to produce energy for common use?
e) What is nuclear fission?
f) Name two substances which are easily fissionable.
g) What are these substances called?
h) What is this phenomenon of breaking up of radioactive isotopes called?
i) Name the rays emitted.
ORAL QUESTIONS
1. Which component of solar radiations produces heat?
2. Name a form of energy that can be harnessed from the oceans.
3. Name the main component of biogas.
4. Name a fuel which is considered cleaner that CNG.
5. What is common between an atom bomb and a nuclear reactor?
6. What is the main transformation of energy during working of a windmill?
LIGHT: REFLECTION AND REFRACTION
Key concepts and terms:
1) Light: light is a form of energy. It brings the sensation of sight. It is a form of
electromagnetic
radiation. It also provides us means of communication (fiber-optics).
2) Light wave: light wave travels with a speed of 3 x 108 ms-1 in free space. Its speed depends
on the medium.
3) Ray and beam: the straight line indicating the path of the light (arrow- direction is called a
ray. A bundle of rays originating from the same source of light in a particular direction is
called a beam of light.
4) Reflection: when light falls on a surface and gets back the same medium, it is called
reflection.
5) Image: the point of convergence or the point form where the light appears to diverge after
reflection or refraction is called image.
6) Angle of incidence: the angle between the incident ray and the normal at the point of
incidence is called angle of incidence.
7) Angle of reflection: the angle between the reflected ray and the normal at the point of
reflection is called angle of reflection.
8) Laws of reflection: 1) the incidence ray the reflected ray and the normal at the point of
incidence, all lie in the same plane.
2) The angle of reflection and the angle of incidence are equal.
9) Aperture: the width of the reflecting surface is called aperture.
10) Focus: the point on the principle axis where all parallel rays meet after reflection is called
principle focus.
11) focal length: the length or separation between the pole and the focus is called focal length
(PF = f)
12) In order to draw ray diagram, two rules are used:
1) The rays of light passing parallel to the principle axis will coverage at the focus after
reflection.
2) The rays of light passing through the focus will emerge parallel to the principle axis after
reflection.
3) The rays of light passing through the center of curvature will all retrace their both after
reflection.(as it is normal at the point of incidence)
4) The rays of light falling at the pole get reflected at the same angle on the other side of
principle axis.(Laws of reflection)
13) Relation between radius of curvature and focal length It is two times the focal length i.e.
R=2f.
1/f = 1/v +1/u where f, v and u are the focal length, image
14) Mirror formula:
distance and object distance.
15) Lens formula: if u, v and f are the object distance, image distance and focal length
respectively
then
1/f=1/v-1/u
16) Magnification of a lens: M=
size of image (h1) / size of object (h0)
m= (h1) / (h0) = v/u.
17) Refractive index = ratio of sine of angle of incidence to sine of angle of refraction
Sin i / sin r = constant
n21 = speed of light in medium 1 / speed of light in medium
2
= v1 /v 2
MAGIC MAP
Oral questions:
1) What is a ray?
2) A Lemon placed in water appears larger in size due to _______________
3) What does the negative sign of magnification of a mirror indicate?
4) What is the relation between focal length and radius of curvature of a spherical
mirror?
5) What is the range of vision of normal human eye?
6) What do you mean by lateral displacement?
115
7) Magnification produced by convex mirror for object of size 5cm is ½ what is the
size of image?
8) What is the real image?
9) A ray of light strikes at 45 degree on a mirror. What is a angle of incidence and
reflection?
10) What is power of accommodation?
i) Rear View mirror ii) magnifying Glass iii) Mirror with Dentist iv) Correction of Myopia .
4. The power of the lens is -2D .What is the focal length and nature of the lens?
MAGIC MAP 2
THE HUMAN EYE AND THE COLOURFUL WORLD
Important Gist :
Human Eye:
It is made up of 3 layers.
 Scleroid : Complete outer layer, 1/3 part is transparent called Cornea.
 Choroid: Vascular incomplete layer
 Retina: Light sensitive incomplete inner layer
EYE PARTS :



Iris : Circular Diaphragm behind Cornea; It controls the size of Pupil.
Ciliary Muscles: Controls Focal Length of Eye Lens & responsible for eye
accommodation.
Lens: biconvex made up of jelly like material
DAY NIGHT VISION
LIGHT
RODOPSIN
RETININ+ OPSIN
DARK
EYES DEFECTS:
 MYOPIA (Near Sightedness)- Image formed before Retina; Corrected by Concave
lens
 HYPERMETROPIA (Far Sightedness) Image formed behind Retina; Corrected by
Convex lens
 PRESBYOPIA – due to aging; ciliary muscles loosens; accommodation power of
eyes decreases; corrected by Bifocal lens
DISPERSION OF LIGHT
Splitting of White Light into its constituent 7 colours.
eg., formation of rainbow, spectrum formation by prism.
NOTE: Dispersion depends on wavelength of light.
Dispersion ∞ 1 / wavelength
SCATTERING OF LIGHT
Bouncing of the light from the atoms or molecules of medium.
Low wavelength light scatters more & vice-versa.
Eg., Sky appears blue in colour.
Sky appears red in evening.
Danger signs are always printed in red colour.
Q-Which part of eye is similar to a camera film?
Q-Which type of image is formed at retina?
Q-What are the functions of rods and cone cells?
Q-What is far point and near point of human eye?
Q-Give reason and correction of following eye defects –
a-Myopia
b- hypermetropia
c-presbyopia
Q- Give reason why sky looks red in the meaning?
CHAPTER No. 1 CHEMICAL REACTIONS AND EQUATIONS
1
Write two examples of every day life where redox reaction are taking place?
Ans: 1) Rusting of iron , iron is oxidized to iron oxide
2) combustion of substance.
Ques 2: A reddish brown vessel developed a green colored solid X when left open in air for a
long time. When reacted with dil H2SO4 , it forms a blue colored solution along with brisk
effervescence due to colourless & odourless gas Z. X decomposes to form black colored
oxide Y of a reddish brown metal along with gas Z, Identify X, Y, & Z.
Ans. 2
X = CuCO3. Cu (OH) 2, Y= CuO, Z= CO2
Ques 3: Grapes hanging on the plant do not ferment but after being plucked from the plant
can be fermented .Under what conditions do these grapes ferment? Is it a chemical change?
Ans: When plucked from the plant, the immune system of the cell loses its efficiency slowly.
In other words, when grapes are attached to the plant aerobic respiration takes place in the
cells as the oxygen reaches there.In the absence of oxygen grapes will ferment. Yes it is a
chemical change
Ques 4: A student has mixed the solutions of lead (II) nitrate and potassium iodide.
(i)
What was the colour of the precipitate formed? Can you name the compound?
precipitated?
(ii)
Write the balanced chemical equation for this reaction.
(iii)
Ans4
2
What type of reaction is it?
(i). Yellow, Lead iodide
(ii)
Pb (NO3)2 + KI --
(iii) Double displacement reaction
PbI2
Observe the following activity & answer the questions.
+ 2KNO3
a.
Do you observe anything happening around the zinc granules?
b.
Is there any change in its temperature?
c.
Why is glass tube not dipped in dil H2SO4?
d.
How is H2 gas collected by downward displacement or upward displacement of
water?
e.
Is H2 gas soluble or insoluble in water?
f.
Is H2 gas heavier or lighter than air?
Ans.5 a ) .Bubbles of hydrogen gas.
b).Yes, temperature will increase.
c.) H2SO4 will rise in glass tube, preventing H2 to evolve
d.) downward displacement
e) Insoluble
f) Lighter than air
.
6 A reddish brown metal X when heated in presence of oxygen forms a black compound Y
which is basic in nature when heated with hydrogen gas gives back X. Identify X & Y.Write
the chemical reaction between Y & H 2. Identify the substance being oxidized & reduced.
Ans.6 Oxygen reacts with copper to form copper oxides which has black colour
2 Cu(s) + O (g)
2 Cuo(s )
The copper (II) oxide is losing oxygen and is being reduced. The hydrogen is gaining oxygen
and is being oxidized.
Ques 7: Why do fireflies glow at night?
Ans:
Fire flies have a special kind of substance that is duciferin that undergoes oxidation (
in the presence of air) in the presence of an enzyme . This reaction is accompanied by the
emission of light. Their fore fire flies glow at night.
8 A student dropped few pieces of marble in dilute HCl contained in a test tube. The gas
evolved was passed through lime water. What change would be observed in lime water?
Write chemical reactions for both the changes observed.
Ans.8
Ca (OH) 2(aq) + CO2 (g)
-
CaCO3(s) + H2O (l)
9.
Astha has been collecting silver coins and copper coins. One day she observed a black
coating on silver coins and a green coating on copper coins. Which chemical phenomenon is
responsible for these coatings? Write the chemical name of black and green coatings
Ans.9 Corrosion is responsible for this coating. Black coating is due to formation of
Ag2S and green coating is due to formation of CuCO3.Cu (OH)2.
Q10 A metal X available in the form of ribbons burns in air with a dazzling white flame, once
heated to its ignition temperature .it leaves a white powder Y , which dissolves in water. The
solution so formed turns red litmus blue. Identify X and Y and write the balanced chemical
equation of the reaction.
Ans: Magnesium ribbon burns with dazzling white light, once heated to its ignition
temperature . The white powder formed is magnesium oxide, which dissolves in water to
give a basic solution. Which turns red litmus blue. Thus X is Mg and Y is MgO.
2Mg + O2 ------- 2MgO
MgO+H2O ------- Mg(OH)2
CHAPTER No.: 2 ACIDS, BASES AND SALTS HOTS:
(High Order Thinking Skill)
Questions with Answers:
1.
Kazi and priyam want to prepare dil H2SO4 .Kazi added conc.H2SO4 to
water slowly with constant stirring& cooling whereas Priyam added water to conc.
H2SO4.Name the student who was correct and why?
Ans.1 Kazi was correct. If water is added to a concentrated acid, the heat generated may cause
the mixture to splash out and cause burns. The glass container may also break due to
excessive local heating.
2.
Compound P forms enamel of teeth. It is the hardest substance of the
body. It does not dissolve in water but it is corroded when pH in the mouth is below 5.5.
How does tooth paste prevent dental decay?
Ans.2 P = Ca3 (PO4)2. Bacteria present in the mouth produce acids by degradation of sugar
and food particles remaining in the mouth after eating. Using toothpastes, which are
generally basic, for cleaning the teeth can neutralize the excess acid and prevent tooth decay.
3.
The oxide of a metal M was water soluble when a blue litmus strip was
dipped in this solution, it did not go any change in colour. Predict the nature of oxide
Ans.3 The Metal oxide (MO) is of basic in nature. It dissolves in water to
form
metal hydroxide as MO + H2O
->
M (OH) 2
B lue litmus does not undergo any change in colour in the basic medium.
4.
A first aid manual suggests that vinegar should be used to treat wasp
sting and baking soda for bee stings.
(i) What does this information tell you about the chemical nature of the wasp stings
(ii) If there were no baking soda in the house, what other household substance could you use
to treat bee stings?
Ans 4: (i) Since vinegar (acetic acid) is used to heal or neutralize the effect of wasp stings this
means that the chemical present in the stings must be some base.
(ii)NH4OH
5.
A road tanker carrying an acid was involved in an accident and its
contents spilled on the road. At the side of the road, iron drain covers began melting and
fizzing as the acid ran over them. A specialist was called to see if the acid actually leaked
into the nearby river.
(a) Explain how the specialist could carry out a simple test to see if the river water contains
some acid or not.
(b) The word melting is incorrectly used in the report. Suggest a better name that should have
been used.
(c) Explain why drain covers began fizzing as the acid rain over them.
Ans : (a) By dipping a strip of blue litmus paper in to the sample of river water.
If the colour changes to red this means that some acid has gone in to the river.
(b) Corrosion.
(c) Iron reacts with acid to evolve hydrogen gas.
.
6.
A few drops of phenolphthalein indicator were added to an unknown
solution A. It acquired pink colour. Now another unknown solution B was added to it drop
by drop and the solution becomes colorless. Predict the nature of A & B.
Ans. 7: Sol `A` is basic in nature as phenolphthalein has imparted pink colour to it. Sol `B` is
an acid it has made solution A colourless by neutralizing by its basic effect.
7.
A student heated a few crystals of copper sulphate in a dry boiling tube.
a) What will be the color of the copper sulphate after heating?
(b) Will you notice water droplets in the boiling tube?
c) Where have these come from?
Ans : (a) White
(b) Yes
(c) Copper sulphate crystals which seem to be dry contain water of
crystallization.
8 A substance `X` used in the kitchen for making tasty crispy pakoras.and is also an
ingredient of antacid. Name the substance `X`.
(i) How does `X` help to make cakes and bread soft and spongy.
(ii) Is the pH value of solution of `X` is lesser than or greater than 7.0?
Ans 10 ( i) When CO2 gas escapes as bubbles it leaves behind pores which make the cake
or
bread soft and spongy.
(ii) It is a salt of strong base so the pH of the solution will be more than 7.0
9 After drinking access of cold drink, a person suffered from acidity. Explain?
Ans: cold drink contains carbon dioxide dissolved in them under pressure. Some amount of
the gas escapes when a bottle of cold drink is opened while a portion of it remain dissolved.
Carbon dioxide dissolved in water forms a weak acid, carbonic acid. Consumption of excess
of cold drink accumulation of carbonic acid in the stomach which is responsible for the
development of acidity
10
Lithium hydroxide is present in the spaceship in which astronaut travel. Explain?
Ans: The carbon dioxide exhaled by the astronauts in spaceship is neutralized by lithium hydroxide.
CHAPTER No. 3
METALS AND NON METALS HOTS: (High Order Thinking Skill)
Questions with Answers:
1 A metal acts as a good reducing agent. It reduces Fe2O3, and MnO2. The reaction with
Fe2O3 is used for welding broken railway tracks. Identify the metal .
Ans 1: Aluminium
2. A yellow coloured powder `X` is soluble in carbon disulfide. It burns with a blue flame
forming suffocating smelling gas which turns moist blue litmus red. Identify `X` and gives
chemical reaction. Identify it is metal or nonmetal.
Ans 2:`X` is sulphur
S + O2 ->
SO2
It is non metal.
3. Nikita took Zn, Al, Cu, Fe, Mg, Na metals & put each metal in cold water and then hot
water. She reacted the metal with steam
(i) Name the metal which reacts with cold water.
(ii) Which of the above metals react with steam?
(iii) Name the metal which reacts with hot water.
(iv) Arrange these metals in order of increasing reactivity.
Ans.3
(i) Na
(ii) Al, Zn, Fe
(iii) Mg
(iv) Na>Mg> Al > Zn > Fe > Cu
4. A student was given Mg, Zn, Fe, and Cu metals. He put each of them in dil HCl contained
in different test tubes. Identify which of them
(i) will not displace H2 from dil HCl
(ii) forms a pale green substance
(iii) will give H2 with 5% HNO3
(iv) will be displaced from its salt solution by all other metals.
Ans4:
(i)
(ii)
(iii)
(iv)
Cu
Fe
Cu
Cu
5. A metal `X` is found in the form of filings which burns vigorously when sprinkle on
flame. When these filings are treated with sulphur a black colured compound `Y` is formed
which is not attracted by magnet. `X` reacts with dil HCl to liberate hydrogen gas. Identify
`X`, `Y``. Write the reaction involved.
Ans5 : Fe + S
`X`
Fe + HCl
->
->
Fe S
`Y`
FeCl2 +H2
6. A, B and C are 3 elements which undergo chemical reactions according to following
equations:
a) A2O3 + 2B
->
B2O3 + 2A
b) 3CSO4 + 2B
->
B2 (SO4)3 + 3C
c) 3CO + 2A
-> A2SO3 + 3C Answer of the following:
i) Which element is most reactive?
ii) Which element is least reactive?
Ans.6 i) Most reactive element is B as it has replaced both A and C from their compounds
ii) Element C is least reactive as it has been replaced both by A and B.
7 An element E combines with O2 to form an oxide E2O, which is a good conductor of
electricity. Answer the following:
i) How many electrons will be present in the outer most shell of E?
ii) Write the formula of the compound formed when it combines with Chlorine.
Ans7 i) Valency of the element E is 1.This means that it has only one electron in the valence
shell.
ii)
E + Cl - >
ECl
Valency of Cl is 1 and Valency of E is also 1.Therefore the formula will be ECl.
8 Why does aluminum not react with water under ordinary condition?
Ans: Aluminum forms a thin tough layer of oxide on its surface. this oxide layer forms a protective
coating on the metal and prevents it from further attack of water.
9 Metal sulphides occur mainly in rocks and the metal halides occur mostly in seas and lakes. What
could be the reason for this?
Ans: Most of the metal sulphides are insoluble in water where as metal halides are generally soluble.
the metal halides( NaCl , MgCl2 etc) are washed away with rain or river water in dissolved state and
so the halide ores occur in lakes and seas.
10
Give the reason why copper is used to make hot water tanks but steel is not?
Ans: this is because iron present in steel reacts with steam to form ferrosoferric oxide whereas
copper has no action with water . as a result of it , the body of steel tank becomes weaker and
weaker in case of iron and not in case of copper.
3Fe
+ 4H2O
-
Fe3O4 +
4H2
CHAPTER -12 ELECTRICITY HOTS
Questions and Answers
Q1. Though same current flows through the electric line wires an the bulb filament, yet only
the filament glows. Give the reason behind it?
Ans. The resistance of electric line wire is very very less than that of the filament of the bulb.
Therefore, the current through the high resistance filament produces more heat which makes
it glow.
Q2. Which is analogous to temperature: a current or electric potential?
Ans. Electric potential is analogous to temperature. As heat flows from higher temperature to
lower temperature, so charges flow from higher potential to lower potential.
Q3. Ammeter burns out when connected in parallel. Give reasons.
Ans. Ammeter consists of a wire of low resistance when connected in parallel; a large amount
of current passes through it hence gets burnt i.e. short circuited.
Q4. For domestic purpose, we connect the electrical devices in parallel instead of connecting
them in series. What are the advantages of connecting electrical devices in parallel?
Ans. By connecting the electrical devices in parallel:1 each device gets the full or same voltage
2. each device gets proper current depending on its resistance.
3. if one device is switched off/on , other electrical appliances remain unaffected
That is why for domestic purpose we connect the electrical devices in parallel instead
of connecting them in series.
Q5. The heating elements of electric toasters and electric iron are made of an alloy rather than
a pure metal. Why?
Ans. The heating elements of electric toasters and electric irons are made of an alloy rather
than a pure metal due to the following reasons:1. Alloys don’t oxidize readily at higher temperature.
2. Alloys have higher resistivity than their constituent elements
Q6. An ammeter is always connected in series across a circuit element. What happens when it
is connected in parallel with the circuit element?
Ans. The ammeter is alow resistance device. When it is connected in parallel, the resistance of
the circuit reduces considerably. Therefore, a large current flows through the circuit, by virtue
of which it may be damaged.
Q7. An electric refrigerator rated 500 W operates 10 hours per day. What is the cost of energy
consumed on the month of june at rs. 3.50 per KWH?
Ans. The total energy consumed by the refrigerator in the month of june
= 500 X 10 X 30 = 150,000 Wh
= 150KWh
Therefore, total cost of energy consumed in the month of june = 150 X 3.50
= rs. 525.00
Q8. A charge of 2C moves between two plates, maintained at a p.d of 1V. What is the energy
acquired by the charge?
Ans. W=QV=2×1=2J
Q9. Why are copper wires used as connecting wires?
ans. The electrical resistivity of copper is low.
Q10. A wire of resistivity ȡ is stretched to double its length. What is its new resistivity?
Ans. It remains same because resistivity depends on nature of material.
Q11. What is the resistance of an ammeter?
Ans. The resistance of an ammeter is very small and for an ideal ammeter, its value is
zero.
Q12. What is the resistance of a Voltmeter?
Ans. The resistance of a voltmeter is very high and for an ideal voltmeter, its value is infinity.
.
CHAPTER -13 MAGNETIC EFFECTS OF ELECTRIC CURRENT
HOTS
Questions and Answers
Q1. Where do we connect a fuse; with alive wire or with a neutral wire. ? what happens if the
fuse wire is connected to the neutral wire?
Ans. Fuse is always connected to a live wire. If fuse wire is connected to neutral wire instead
of live wire then even when the fuse burns out the appliance remains connected to the live
wire and the current supplied will not be disrupted due to overloading.
Q2. In a three pin plug, the earth pin is thicker and longer than the live and neutral pins. Why?
Ans. The earth pin is thicker so that it doesnot enter into the live of neutral sockets. It is
longer so that the earth connection is made first. This ensures the safety of the users.
Q3. A straight wire carrying electric current is moving out of plane of paper and
is perpendicular to it. What is the direction and type of induced magnetic field?
Ans. Induced magnetic field will be in the form of concentric circles in the plane of paper.
Q4. How can it be shown that magnetic field exist around a wire carrying current?
Ans. By using magnetic compass which, shows deflection.
Q5. How can a solenoid be used to magnetise a steel bar.
Ans. By inserting the steel bar inside the solenoid and switching on electric current.
.
Q6. Why can’t two magnetic field lines ever intersect?
Ans. If so then at the point of intersection there will be two different directions of magnetic
field which is not possible.
Q7. Can a 5 A fuse be used in wire carrying 15 A current? Why?
Ans. No, because both of them would then be ineffective in controlling the amount of current
flowing.
Q8. A current-carrying straight conductor is placed in the east-west direction. What will be
the direction of the force experienced by this conductor due to earth’s magnetic field? How
will this force get affected on?
(a) reversing the direction of flow of current
b) doubling the magnitude of current.
Ans. The direction of earth’s magnetic field is fron G- south to G-north. Let current is from
west to east, force is vertically upwards.
(a) By reversing the direction of the current, the direction of the force will be reversed i.e.
vertically downwards.
(b) The magnitude of the force is doubled.
Q9. An electron enters a magnetic field at right angles to it as shown in fig. The direction of
the force acting on the electron will be:
(a) to the right
(b) to the left
(c) out of the page (d) into the page
Ans. When a conductor carrying current is placed perpendicular to the direction of magnetic
field, the acting on it is given by Fleming’s left hand rule. Since the direction of current is
the same as that of the motion of a positive charge, the direction of force acting on it when
moving perpendicular to the direction of magnetic field is the same as that acting on a
current-carrying conductor placed perpendicular to the direction of magnetic field.
Obviously, the force acting on an electron is opposite to that. Therefore in this case it is into
the page.
Q13. A coil of insulated copper wire is connected to a galvanometer. What would happen if a
bar magnet is
(i)
Pushed into the coil?
(ii)
Withdrawn from inside the coil?
(iii)
Held stationary inside the coil?
Ans. (i) Due to change in magnetic flux linked with coil, the galvanometer shows deflection
(say towards right).
(ii) Due to change in magnetic flux linked with coil, the galvanometer shows deflection
(say towards left opposite to that in case one).
(iii) As it is stationary no change in magnetic flux linked with coil, so galvanometer shows
no deflection
CHAPTER-8 HOW DO ORGANISMS REPRODUCE?
HOTS: (High Order Thinking Skill)
Questions with Answers
Q.1) How does bryophyllum multiply vegetatively?
Ans- By Leaveswhich bear adventitious buds.
Q-2 What is normal fertility period in human female/
Ans- 14 – 16 days of menustrual cycle.
Q-3 Draw a neat diagram of human female reproductive system.
Ans- Well laballed diagram
Q.4) Why is variation beneficial to the species but not necessary for the individual?
Ans- Variation is beneficial to the species as it enables a species for its survival. A
favourable variation makes an organism to live better in a changed environment and an
unfavourable variation will not. So it is not necessarily true that a variation is beneficial to
the individual always.
Q.5) What is the advantage of reproduction through spores in the case of Rhizopus?
Ans- The spores are covered by thick walls that protect them until they come into contact
with aother moist surface and can begin to grow.
Q.6) The simple animals such as planaria can be cut into number of pieces and each piece
grows into a complex organism. What is this process known as?
Ans- Regeneration
Q.7) Name the unicellular organism which cause the disease known as kala-azar.
Ans- Leishmania
Q.8) Which process taking place in the nucleus of a cell leads to variation in the offspring
during reproduction?
Ans- DNA copying
Q.9) What causes joining up of stock and scion in grafting technique of vegetative
propagation in plants? Define the terms stock and scion. Name one positive trait each of the
plant contributing scion and stock should have.
Ans- The stock and scion unite due to cambial cavity. Stock is the portion on which grafting
is done and it provides the roots. Scion is the portion of the plant which is grafted on the
other plant and it contributes the stem. The plant contributing scion should have large sized
fruits and the plant contributing stock should have deep root system.
Q.10) Which type of layering is done in Jasmine?
Ans- Air Layering (Gootee)
Q.11) Where does fertilization takes place in human female?
Ans- Oviduct (fallopian tube)
Q.12) Why is it said that “sexual reproduction promotes diversity of characters in the
offsprings”?
Ans- It is because sexual reproduction results from the fusion of two gametes coming from
two different and sexually distinct individuals. This leads to variation, is necessary for
evolution.
Q.13) What happens if the fallopian tubes are partially blocked and the ovulated eggs are
prevented from reaching the uterus?
Ans- Fertilization may take place but the zygote may develop in the tube instead of uterus.
Q.14) Name the causative organism of syphilis and gonorrhoea.
Ans- Treponema pallidum and Nisseria gonorrhoeae.
Q.15) What happens to the ovum , mensutruation and ovulation after the fertilisation?
Ans- Ovum forms zygote which fixes itself in the walls of the uterus and start to develop as
an embryo and menstruation and ovulation stops.
CHAPTER – 9 HEREDITY AND EVOLUTION
HOTS: (High Order Thinking Skill)
Questions with Answers:
Q.1 Name the organism in which feathers appeared for the first time?
Ans- Members of Dromaesaur family, which were small dinosaurs.
Q-2 A husband has 46 chromosomes, his wife has 46 chromosomes. Then why don’t their
offsprings have 46 pairs of chromosomes, which is obtained by the fusion of male and
female gametes. Support your answer with neat illustration.
Ans- At the stage of gamete formation reduction division occurs which reduces the
chromosomes no. to half. ( well illustrated diagram).
Q-3. What is called phylogenetic system of classification?
Classification based on evolutionary relationships of organisms.
Q-4. Is it true that when a new species is emerged, the old species is eliminated and why?
Ans- No,it is not true that when a new species is emerged, the old species is eliminated.
Because when there is a change in any species, the change is only in a part or a few
members of the species population. If the newly generated species after genetic change is
better in any way, it will get more opportunity to survive and if the genetic change is against
the environment, it will die. Thus, unchanged members of other species may also remain and
tend to live in changed environment.
Q-5. The gene type of green stemmed tomato plants is denoted as GG and that of purple
stemmed tomato plants as GG when these two are crossed.
i. What colour of stem would you expect in F1 progeny?
ii. Give the percentage of purple stemmed plants if F1 are self pollinated. iii. In what ratio
would you find the gene types CG and Gg in the F2 progeny?
Ans- i. Colour of F1 progeny – Green
ii. Percentage of purple stemmed plants in F2 generation ¼ or 25%. iii. Ratio of genotypes
GG and Gg 1:2
Q-6. The human hand, cat paw and horse foot when studied in detail show the same structure
of bones and point towards a common origin.
i. What do you conclude from this?
ii. What is the term given to such structures?
4Ans- (i) They have a common ancestry
(ii)Homologous organs
Q-7 What are the causes of variations in clones?
Ans-. i. inaccuracies during DNA copying
ii. Effect of environment termed acquired variation.
iii. Mutations are sudden stable changes which are discontinuous inheritable as
produced due to changes in genetic make-up
Q-8. How do we know how old a fossil is?
Ans. There are two methods:
i. Relative method when we dig into the earth, the fossils we find closer to the surface are
more recent than the fossils we find in deeper layer
ii. By detecting the ratios of different isotopes of the same element in the fossil material.
Q-9. Study the given data and answer the questions following the data:
Parental plants cross fertilised and seeds collected F1 First offsprings Generation
F2
Offsprings of self pollination of F1Male
parents always bare red flowers.Female parent
always had white flowers. 330 seeds observed. All 330 flowers. sown and gave red Out of 44
seeds 33 seeds gave plants with red flowers and 11 seeds gave plants with white flowers.
i. What is the term for this type of cross?
ii. What does the data of the column marked F1 indicate?
iii. Express the gene type of the (a) parents (b) F1 progeny and (c) F2 progeny
Ans- i. Monohybrid cross
ii. Red colour of flower dominant over white flower
iii. a. Parents – (RR) and (rr)
b.F1 progeny – Rr
c.
F2 progeny – RR, Rr and rr
Q-10. Name a recessive trait which is quite common in human beings.
Ans- Blood group O.
CHAPTER – 15 OUR ENVIRONMENT
HOTS
Questions and Answers
Q.1 Which trophic level eats nothing and which one is not eaten?
Ans- Eats nothing – Producers
Not eaten - - Top carnivores.
Q2. What are transducers?
Ans- Plants are known as transducers because they convert solar energy into chemical
energy.
.. Q3. What will happen if decomposers are not there in the environment?
Ans-. If decomposers are not there in the environment, the breakdown of the complex organic
substances into simple substances will not take place and natural replenishment of the soil
will not take place. So, presence of decomposers is essential for the replenishment of soil
and biogeochemical cycle of elements or substances.
Q4.
What is the harm of clay cups?
Ans- Clay cups cause depletion of top fertile soil as they are formed from the same.
Q 5.What will happen if all the carnivores are removed from the earth?
Ans- If all the carnivores are removed from the earth, the population of herbivores will
increase. Large population of herbivores will overgraze. As a result, all plants will
disappear from the earth surface and ultimately the earth may become a desert. The
biosphere will get disturbed which will lead to end of life on earth.
Q6. Write the harmful effects using plastic bags on the environment. Suggest alternatives to
plastic bags.?
Ans- i) Plastic bags when buried under soil ,the area becomes barren and leads to soil
pollution.
ii) Plastic bags often block drains causing foul smell and source of spread of diseases.
iii) On burning they release gases that causes pollution.
Alternatives----Use of cloth , jute and paper bags to carry things.
Q7. The number of malarial patients in a village increase tremendously, when a large number
of frogs were exported from the village. What could be the cause for it? Explain the help of
food chain?
Ans-. Phytoplankton
Zooplankton
Mosquito larva
Frog
In the absence of frog, more mosquito larva survive, giving rise to large number of
mosquitoes which cause increase incidence of malaria.
Q8. State one reason to justify the position of man at the apex of most food chains?
Ans- The position of man is at the apex of most food chains as he is an intelligent organism
and can take any advantageous position by manipulation.
Q9. Name the process that is a direct outcome of excessive burning of fossil fuels?
Ans-. Global warming is a direct outcome of excessive burning of fossil fuels.
Q10. If all the wastes we generate is bio-degradable what impact may this have on the
environment?
Ans-.Cleaner environment without any pollution, more nutrients will be released into the
nutrient pool, will help to maintain ecological balance.
Q11. Write the harmful effect of ozone depletion.
Ans-. 1. Cause the skin cancer
2. Damage to eyes
3. Immune system
Q12. Why food chains consists of three or four steps only?
Ans- Since so little energy is available for the next level of consumers and for this reason
food generally consists of three or four steps. The loss of energy at the each step is so great
that very little usable energy remains after four tropic levels.
Q13. Which of the following will have the maximum concentration of harmful chemicals in
its body?
Peacock, Frog, Grass, Snake, Grasshopper
Ans-.Grass, Grasshopper , Frog , Peacock
Peacock will have maximum conc.
CHAPTER-16 MANAGEMENT OF NATURAL RESOURCES
HOTS
Questions and Answers
Q1 What is GAP?
Ans- Ganga Action Plan.
Q2- What are five F’s of chipko movement?
Ans- i) Food
ii) Fodder
ii) Fuel
iv) Fibre
v) Fertiliser.
Q3- Write any two alternatives to dams.
Ans- Adopting water harvesting techniques and reducing the scale of floods through better
catchment management.
Q4- Why do you think there should be equitable distribution of resources?
Ans- We think that there should be equitable distribution of resources because not only a
handful of rich and powerful people, but all the people may get benefit from the development
of these resources.
Q5- Which canal has brought greenery to considerable areas of Rajasthan?
Ans- Indira Gandhi Canal.
Q6- How did Chipko Andolan ultimately benefit the local population? Give any three
benefits?
Ans-
(a.) The locals benefitted from forest produces
(b) The wild life and nature were conserved
(c) The quality of air and soil was preserved
Q7- Quote three instances where human intervention saved the forests from destruction.
Ans-
a.) Contribution of Bishnoi movement
(b) Building national parks
c) Encouraging wildlife sanctuaries
Q8- Why are environmentalists insisting upon sustainable natural resource management?
Give any four reasons.
Ans- a. Non-renewable resources are limited, we should use them judiciously
b. We should encourage the use of renewable resources
c. We should preserve the environment for future generation
d. The benefits of the controlled exploitation should go to local people
CHAPTER No. 4 Carbon and its compounds HOTS
(High Order Thinking Skill)
Questions with Answers:
1. What would be observed by adding 5% solution of alkaline potassium permanganat drop
by drop to warm ethanol taken in atest tube?
Ans On adding 5% solution of alkaline potassium permanganate to ethanol,it will be
oxidized to ethanoic acid.The pink colour of the solution will be discharged upon
warming.
CH3CH2OH + 2[O]  CH3COOH + H2O
2. An organic compound ‘A’ is widely used as a preservative in pickles and has a molecular
formula C2H2O2. This compound reacts with ethanol to form a sweet smelling compound ‘B.
(i)
How
can
we
get
compound
‘A’
back
from
‘B’?
(ii)
Which gas is produced when compound ‘A’ reacts with washing soda?
Ans : ( i)Esters react in the presence of an acid or a base to give back the alcohol and
carboxylic acid.
(ii)
CO2
3. Hydrocarbon `X` and `Y` having molecular formulae C3H8 and C3H6 respectively. Both
are burnt in different spatula on the bunsen flame. Which will produce sooty flame.Identify
`X` and `Y`.
Ans: `Y` will burn with a sooty flame. So it is an unsaturated hydrocarbon.
Propane (X)
Propene (Y)
Q4. ( i) State one advantage of soaps over synthetic detergents.
(ii) Name two homologous series which are collectively called as carbonyl compounds.
Ans (i) Soaps are biodegradable while detergents are not.
(ii)Aldehydes and ketones
5. `A` compound works well with hard water. It is used for making shampoos & products for
cleaning clothes. A is not 100% biodegradable and causes water pollution. `B` does not work
well with hard water. It is 100% biodegradable and does not create water pollution. Identify A
& B.
Ans . A is detergent & B is soap
Q 6. Give a test that can be used to differentiate chemically butter from vegetable oil.
Ans Vegetable oil is an unsaturated compound while butter is saturated compound so we
can distinguish them by hydrogenation, bromine water test or Bayer’s reagent test.
7. A compound `X` with molecular formula C2H4 burns with a sooty flame. It decolourise
bromine water. Identify `X`. Will it dissolve in water or not? Will it conduct electricity in aq.
Solution? Will it have high melting point or low melting point ?
Ans : `X` is ethene. It will neither in water nor conduct electricity because it is a covalent
compound. It has low melting point dissolve.
8. An organic acid ‘X’ is a liquid which often freezes during winter time in cold countries. It
acid,a compound ‘Y’ with a sweet smell is formed.
1) Identify X & Y.
2) has molecular formula C2H4O2.On warming with ethanol in the presence of
few drops of sulphuric Write chemical equation for this reaction involved.
Ans :Organic acid X with molecular formula C2H4O2 is ethanoic acid while substance Y is
ethyl ethanoate which is formed when ethanol is warmed in the presence of sulphuric acid.
CH3COOH + C2H5OH + H2SO4  CH3COOC2H5 + H2O.
9. How can ethanol and ethanoic acid be differentiated on the basis of their physical
chemical properties?
and
Ans : Based on physical properties;
Ethanol has lower boiling point than ethanoic acid because in ethanoic acid,the
intermolecular forces are strong due to the presence of hydrogen bonding.
Based on chemical properties;
Ethanoic acid gives effervescence with sodium bicarbonate while ethanol does not.
10.Give reason for the following observations:
a) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the
flame
b) Use of synthetic detergents causes pollution of water.
Ans : a) We need to adjust air holes of gas burner so that sufficient oxygen – rich mixture is
burnt to give a clean blue flame for complete combustion.
b) Synthetic detergent are generally non-biodegradable, that is, they are not decomposed
by microorganism like bacteria.Hence,use of synthetic detergent causes water
pollution in the lakes and rivers.
CHAPTER – 5
PERIODIC CLASSIFICATION OF ELEMENTS HOTS:
(High Order Thinking Skill)
Questions with Answers:
Q-1 A and B are the two elements having similar properties which obey Newlands law of
octaves. How many elements are there in between A and B?
Ans : Six elements.
Q-2. X, Y and Z are the elements of a dobereiners triad. If the atomic mass of x is 7 and
that of z is 39, what should be the atomic mass of y?
Ans : (7 + 39)/ 2 = 46/2
y = 23.
Q-3. Two elements X and Y have atomic numbers 12 and 16 respectively. Write the
electronic configuration for these elements. To which period of the modern periodic table do
these two elements belong? What type of bond will be formed between them and why?
Ans : X (Z=12): 2, 8 , 2
Y (Z=16): 2, 8, 6
Both these elements are present in third period. An ionic bond is formed between X &
Y as a result of transfer of two electrons from X to Y.
Q -4. Why do you think the noble gases are placed in separate groups?
Ans : Since the noble gases are the least reactive elements and they have most stable
electronic configuration so they have been placed on the right side in the periodic table as
zero group element.
Q-5. An element X (2,8,2) combines separately with NO3 and (SO4)2 -, (PO4)3 - radicals.
Write the formulae of the three compounds so formed. To which group of the periodic table
does the element ‘X’ belong? Will it form covalent or ionic compound? Why?
Ans : X (NO3)2
: XSO4
X3(PO4)2
X belong to second group . X forms ionic compound because by losing two electrons
X achieve the electronic configuration of Noble gas element Neon.
Q6 A) Name any two elements whose existence was predicted by mendleev?
B) Which alkali element has smallest size?
Ans A) Scandium and gallium
B) Lithium
Q 7. A metal M forms an oxide having the formula M2O3. It belongs to 3rd period in the
modern periodic table. Write the atomic number and valency of the metal.
Ans : Atomic number = 13
Valency = 3
Q-8. Helium is unreactive gas and neon is a gas of extremely low reactivity. What if anything
do their atoms have in common?
Ans Both the gases are inert gases as their outermost shells are completely filled. Both these
gases are monoatomic gases .
Q-9. Why do you think the noble gases are placed in separate groups?
Ans Since the noble gases are the least reactive elements and they have most stable electronic
configuration so they have been placed on the right side in the periodic table as zero group
elements.
Q10. A metal M forms an oxide having the formula M2O3. It belongs to the third period in
the modern periodic table.Write the atomic number and the valency of the metal.
Ans a) Aluminium
b)Atomic no.13 and
c)valency is 3+
Q-11. Name two elements you would expect to show chemical reaction similar to magnesium.
What is the basis of your choice?
Ans Ca & Sr will have properties similar to Mg because both these elements have same no.of
valence electrons as that of magnesium i.e.all the three elements have two electrons in their
valence shell.
The following is Newland’s Octave Table. Observe it and answer the following questions:
sa(do)
re(re) ga (mi)
ma (fa)
pa(so) da ( la)
ni(ti)
H
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
K
Ca
Cr
Ti
Mn
Fe
Co ,Ni
Cu
Zn
Y
In
As
Se
Br
Rb
Sr
Ce and La
Zr
i.
Which of the element in 1st column has different properties from rest of the elements?
ii.
Which of the elements resemble with each other in second column?
iii.
Pick up odd element in second last column.
iv.
Pick up elements which have similar properties in last column.
Ans 3: (a) Co & Ni
(b) Li, Na , K
(c) Mn
(d) O, S, Se.
Q-12. Is it possible to have an element with atomic number 2.5?
Ans : No,because the atomic number of elements are always in whole numbers.
Chapter10
LIGHT REFLECTION & REFRACTION
HOTS
1. Power of a lens is a measure of the ability of the lens to converge the rays of
light falling on it. Quantitatively, power of a lens = reciprocal of focal length of
lens, i.e., P = ⅟f. if a lens happens to diverge the rays of light falling on it, its
power is said to be negative. Thus , power of a convex lens is positive and
power of a concave lens is negative.
If P₁, P₂ are powers of two lenses held in contact with each other, the power of
the combination is P = P₁ +P₂. Note that P₁, P₂ are to be added with proper sign.
Read the above passage and answer the following questions:
i)
What is the SI unit of power?
Ii) Focal length of a concave lens is 20 cm. What is its power?
ii)
What lessons of life do you learn from the relation P =P₁+P₂?
Ans i)SI unit of power is diopter (D). 1 diopter is the power of a lens of focal
length one metre.
(ii) Here, f = -20 cm = -20/100 m = -1/5 m. P =⅟f = ⅟-₁/5 = -5D
(iii)If P₁=3D and P₂=-2D, then
P=P₁+P₂ =3D -2D=1D
Again, if P₁=3D and P₂=2D, then
P=P₁+P₂=3D+2D=5D
i.e., power of combination is much larger when the two lenses are of
same nature. The same is true in real life. To make a powerful
combination in business, partners should preferably be of same
nature. Same is true for life partners, i.e., husband and wife. If their
nature is identical, they will make an adorable couple.
2.. A glass slab is placed over a thick straight line drawn on a sheet of white
paper placed on a table. The straight line makes an angle with the edges of the
glass slab as shown in figure, What do you observe, when you look at the
portion of the line under the glass slab from the sides ? Explain the reason of
your observation.
When we look at the portion QR of the line under the glass slab from the sides
we observe that the line is bent at the edges Q and R as shown in figure. This is
because of the refraction of light when light goes from one medium to another
medium.
3.A glass slab is placed over a thick straight line PQRS drawn on a white paper
placed on a table. The straight line is perpendicular to the edges of the glass
slab. Does the portion of the line under glass slab appear bent ?
The portion QR of the straight line under glass slab does not appear to be bent.
This is because, incident ray PQ is perpendicular to the glass slab, so < I = 0.
Hence, angle of refraction is also zero. Therefore, no refraction of light takes
place at Q and hence no bending of ray of light. Similarly, QR ray of light is also
perpendicular to the glass slab and hence there is no refraction of light at R.
4.15. A thick straight line PQRS is drawn on a white paper placed on a table. A
glass slab is placed over this line such that the line is perpendicular to the edges
of the glass slab as shown in figure. Look at the portion QR of the line under
glass slab from the top of the glass slab. What do you observe about this
portion QR of the line
We observe that the portion QR of the line is raised as shown in figure. This is
because of the refraction of light.
5. Read the above passage and answer the following questions:
I)Do the rays passing through principal focus of mirror fall normally on
the mirror?
II)Which is closer to the mirror, principal focus or centre of curvature
of the mirror?
III)What values of life do you learn from this concept?
ANS: I)No, the rays passing through principal focus of mirror do not
fall normally on the mirror.
II)Principal focus F of the mirror is closer to the pole P of the mirror,
compared to the centre of curvature , C.
Infact ,PF = ⅟2PC.
III)This concept implies that one should preferably stay along normal
to avoid deflections. Staying in normal mod will save you from large
scale fluctuations. They say, too much of everything is bad. So eat
normal, sleep normal, play normal, study normal, talk normal, listen
normal and so on. Prefer not to do anything abnormally.
6. Why do different colors deviate through different angles on passing
through a prism?
Ans This is because different colors travel through glass with different speeds
and glass has different refractive index for different colors.
7..Describe an activity to make a coin visible at the bottom of a bucket half
filled with water, which was not visible when you look at the coin from one side
above the water.
(i) Place fifty paisa coin at the bottom of a bucket half filled with water.
(if) Place your eye at one side of the bucket and look at the water in the bucket
as shown in figure A. You will
not see the coin in water.
(iif) Now keep your eye at the same position and ask your friend to pour more
water in the bucket.
(iv) You will see the coin in water at I when the bucket is almost filled with
water as shown in figure.
Conclusion.This activity shows that the distance through which an object (say
coin) appears to be raised in water increases with the increase in the real depth
of the object
8.Write any two uses of concave and convex lens. Parallel rays of light incident
on a concave mirror and a convex mirror as shown in figure, (i) Redraw the
reflected rays in both the cases, (ii) Name the points where the reflected rays
meet or appear to meet on the principal axis (iii)You are given a convex lens
and a black paper. A teacher asks you to bum the paper in sun light. Draw ray
diagram to show that paper burns in sunlight
Ans:- uses of concave & convex lens:
a)Concave mirrors are commonly used in torches, search-lights and vehicles
headlights to get powerful parallel beams of light. They are often used as
shaving mirrors to see a larger image of the face. The dentists use concave
mirrors to see large images of the teeth of patients. Large concave mirrors are
used to concentrate sunlight to produce heat in solar furnaces.
b) Convex mirrors are commonly used as rear-view (wing) mirrors in vehicles.
These mirrors are fitted on the sides of the vehicle, enabling the driver to see
traffic behind him/her to facilitate safe driving. Convex mirrors are preferred
because they always give an erect, though diminished, image. Also, they have a
wider field of view as they are curved outwards. Thus, convex mirrors enable
the driver to view much larger area than would be possible with a plane mirror.
Reflected rays are shown in
figures.
(ii)The point where the reflected rays of light meet or appear to meet on the
principal axis is known as principal focus F of the concave mirror or convex
mirror.
(iii).
9. i)The principal focus of a convex mirror lies at the back of the mirror. Why ?
ii) The magnification produced by a spherical mirror is positive. Explain whether
the image formed by the mirror is erect or inverted.
iii)'A light of wavelength A enters: water from air. Explain, whether the
wavelength of light in water (a) increases, (b) decreases, (c) remains the same.
𝜆
𝜇=
𝜆𝑚
Ans .In case of a convex mirror, a parallel beam of light after reflecting from the
mirror appears to come from a point at the back of the mirror. This point is the
principal focus of the mirror.
ii)Magnification produced by the spherical mirror,
𝑠𝑖𝑧𝑒𝑜𝑟ℎ𝑒𝑖𝑔ℎ𝑡𝑜𝑓𝑡ℎ𝑒𝑖𝑚𝑎𝑔𝑒
m = 𝑠𝑖𝑧𝑒𝑜𝑟ℎ𝑒𝑖𝑔ℎ𝑡𝑜𝑓𝑡ℎ𝑒𝑜𝑏𝑗𝑒𝑐𝑡
heights of the image and the object are positive. This is possible if image is
erect as object is always assumed to be erect. Thus, the image formed by the
mirror is erect.
(iii) λ = Wavelength of light in air
λm = Wavelength of light in water
𝜇 = Refractive index of water
λm = λ/n
since n > 1 , so λ m = < λ
Thus, wavelength of light in water decreases.
10.I)State the relation between the refractive index (n) of a medium, speed of
light in air (c) and speed of light in medium.
II)Refractive index of glass with respect to air is 1.5. What is the refractive index
of air with respect to glass ?iii)What is the angle between the incident ray of
light and the emergent ray of light, when incident ray of light falls obliquely on
the glass slab ?
iv) State the relation between the focal length (f) and power of a lens.
v) A ray of light falls obliquely on the glass slab. The perpendicular distance
between the emergent ray of light and the original path of the incident ray is 2
mm. What is the lateral displacement of the my of light ?
Ans i) n = c/v
nga = 1.5. Therefore, 1/nag= 1/1.5 = 0.67..
III) When incident ray of light falls obliquely on the glass slab, then the
emergent ray of light is parallel to theincident ray of light. Therefore, angle
between the incident and emergent rays of light is zero
iv)P =
1
𝑓(𝑖𝑛 𝑚)
=
100
𝑓(𝑖𝑛 𝑐𝑚)
v)Lateral displacement of the ray of light = 2mm.
chapter 11
Human eye and the colourful world
HOTS
Q1.What happens to the image distance in the eye ,when we increase the
distance of an object from the eye?
ANS.For a normal eye, image distance in the eye is fixed ,being equal to
distance of retina from the eye lens .When we increase the distance of an
object from the eye , the focal length of eye lens is changed on account of
accommodation power of the eye ,so as to keep the image distance constant .
Q2. What is meant by accommodation of human eye ?How is it achieved?
ANS. Accommodation or power of accommodation of human eye is the ability
of the eye to observe distinctly the objects situated at widely different
distances from the eye.This property id due to the action of ciliary muscle s
holding the eye lens.
For observing distant objects ,eye is in relaxed state i.e unaccommodated . The
eye lens is thin and image of distant objects is formed on the retina.
For observing nearby objects ,the ciliary muscles contract the eye is in a state
of tension . It is said to be accommodated
Q3.What is meant by range of vision ? What is its value for a person with
normal vision?
ANS. The vision of a person is the distance between near point(N ) and far
point (F) of his eyes .The point at closest distance , at which an object can be
seen clearly by the eye is called near point (N) of the eye.
The most distant point at which an object can be seen clearly is called far point
(F) of the eye. For a normal eye , far point lies at infinity . Therefore, for a
person with normal vision , the range of vision is infinite.
Q4. Calcualte maximum power of accommodation of a person having normal
vision.
ANS. For a person having normal vision , least distance of vision is d=25 cm.
i.e maximum power of accommodation ,
P=100/f
=100/d =100/25 =4 dioptre
Q5.Why we cannot read a printed page by holding it very close to our eyes ?
ANS. When we hold a printed page very close to our eyes ( at distances less
than 25 cm; which is least distance of distinct vision of normal eye), we may see
a blurred image and also feel strain in the eyes. This is because focal length of
the eye lens cannot be decreased below a certain minimum limit.
Q6. A person cannot see the objects distinctly, when placed at a distance less
than 100cm.What is power of the spectacles that he should use to see clearly
the object placed at 25cm?
Ans –Here distance of near point,
x’=100 cm
Distance of object, d =25 cm
Power, P =? Focal length , f = ?
As
f=x’d/x’-d
f=100x25/1OO-25 =100/3
as P =100/f
i.e P =100/100/3 = 3 D
The corrective lens is convex.
Q7. A person is able to see objects clearly only when these are lying at a
distance between 50 cm and 300 cm from his eye.
(a)What kind of defect of vision he is suffering from?
(b)What kind of lenses will be required to increase his range of vision from 25
cm to infinity ?explain briefly
ANS.(a)For a normal eye , the near point is at 25 cm and the far point is at
infinity from the eye . The given person cannot see objects clearly either closer
to the eye or far away from the eye .so, he is suffering from both myopia and
hypermetropia.
(b)A bi-focal lens consisting of a concave lens and convex lens of suitable focal
length will be required to correct the defect and to increase his range of vision
from infinity in a bi -focal lens upper portion is concave which correct distant
vision and lower portion is convex which corrects near vision
8. A glass prism is able to produce a spectrum when white light passes through
it but a glass slab does not produce any spectrum . Explain why is it so?
Ans. When white light enters the glass slab, dispersion of light take place. The
angle of refraction for violet color is more than for red color on entering the
glass slab. But all colors of light return to the original direction of propagation
while refracting from other side of the slab and thus white light emerges out of
the glass . Hence, slab does not produce any spectrum.
Q 9. An eye donation camp is being organized by social workers in your locality
. How and why would you help in this cause?
Ans. Reasons for donating eyes:
i)
ii)
A person’s corneal blindness can only be elevated by a human donar’s
cornea.
It is opportunity to restore someone’s sight.
Methods for supporting this cause:
i)
Make it a family tradition of donating the eyes .
ii)
Motivate and educating others about eye donation.
iii)
Help removing all the myths about eye donation.
10. Name one defect of vision which cannot be corrected by any type of
spectacle lenses?
Ans. Cataract
11. State one effect produced by the scattering of light by the atmosphere ?
Ans Tyndall effect
Minimum Learning Package
Chapter 6 : Life Processes1
1)
Write one feature which is common to each of the following pairs of terms/ organs
(i)
Glycogen and starch
(ii)
Chlorophyll and haemoglobin
(iii)
Gills and lungs
Ans. (i)Reserve food (glycogen in animal cell and starch in plant cell)
(ii) Both are pigments (Chlorophyll is photosynthetic pigment while
haemoglobin is respiratory pigment present in blood.)
2) What is the action of intestinal juice on the following:
Proteins
--- A------------Complex carbohydrates --- B------------Fats
--- C-----------Ans. A = Amino acid
B
= Glucose
C
= Fatty acids and glycerols
3) Give one word for the following:
(i)
I am secreted from the walls of stomach . I kill all the harmful germs present in
food and help my friend pepsin to work in acidic medium
(ii)
We are biocatalysts we enhance the rate of metabolic activities
(iii)
We push the food forword by rhythmic contraction
Ans. (i) Hydrochloric acid
(ii) Enzymes
(iv)
Peristaltic movements
4) Name the green dot like structure in some cells observed by student when a leaf peel was
viewed under a microscope what is this green color due to?
Ans. The green dot like structures are chloroplasts .This green color is due to the presence
of a green pigment called chlorophyll. Chlorophyll is present in cell organelles called
chloroplasts.
(iv)
Both are organs meant for breathing(gills in fish and lungs in birds and
animals)
5.What happens to the breathing rate during vigorous exercise?
Ans. During vigorous exercise the breathing rate increases to supply more and more oxygen
to the cells as lot of energy is being used up during exercise .
6. State one word for the following:
(i)
Mechanism for moving the air in and out of the body
(ii)
Structure in plants to facilitate gaseous exchange
Ans.(i) Breathing
(ii) Stomata
7. How is small intestine designed to absorb digested food?
Ans. The inner surface of small intestine has millions of tiny, finger like projections called
Villi. The presence of villi gives the inner walls of the small intestine a very large surface area.
The large inner surface area of small intestine helps in the rapid absorption of the digested
food.
8 .How food is transported in plants?
Food is transported in dissolved form through phloem.
9 .State any one difference between autotrophic & heterotrophic modes of nutrition?
Autotrophic nutrition (i) In this type of nutrition organism can prepare their own food.(ii)
Chlorophyll is required.
Hetrotrophic nutrition i) In this type of nutrition organic food is obtained from outside(ii)
Chlorophyll is not required.
10.How are fats digested in our body? Where does this take place?
(a)Fats are emulsified by Bile salts.The emulsified fats are acted upon by Pancreatic &
intestinal lipase to form fatty acids and glycerol
(b)Digestion of fats occur mostly in jejunum (part of small intestine)
11.What is the role of HCl in our stomach?
HCl provides acidic medium,kills germs & activates the enzyme pepsin
12.State two vital functions of human kidney?
Osmoregulation,Filteration
13.Write one function each of the following components of transport system in human
beings?
(a)Blood vessels, (b)Blood platelets c)lymph d) heart
A) Blood vessels: Transport the blood btn heart & various organs
(b)Blood platelets:Help in blood clotting
(c) Lymph: Carries digested fats,fight infections,drains excessive extra cellular fluid back into
the blood.
(d)Heart: Receive blood from body through veins & pumps blood with enough force into
major arteries so that it reaches every part of the body.
14.Diagrams:
(a)Human digestive system
(b)Human respiratory system
(c)Human excretory system
(d)Str.of nephron
(e)Human heart
15.Why human blood circulation called double circulation?
The blood flows twice through the heart in human beings so it is called double circulation.
Inferior blood-----Right auricle-----Rt.ventricle-----Pulmonary artery----lungs
(Pulmonary circulation)
Lungs-----Pulmonary vein-----Left auricle-----Lft. Ventricle------Aorta----Body
(Systemic circulation)
CHAPTER 8. HOW DO ORGANISMS REPRODUCE
1) Full form of IUCD
Intra utrine contraceptive device
2.Give two functions performed by ovaries in human females?
(i) Formation of ova (ii)secretion of hormones-estrogen,progesterone.
3 Name any two types ofasexual reproduction?
Fission,spore formation
4state the method used for growing rose plant?
1) Cutting
2) Grafting
5Mention the importance of DNA COPYING in reproduction?
It provide equal set of genes in the daughter cells
6) What are sexually transmitted diseases? Name any three. Which one of them
damages immune system of our body?
The diseases which are transmitted through sexually contact with infected person.E.g
Gonorrhoea.Syphilis.AIDS.
Damage to the immune system is caused by HIV.
7)Name various methods of contraception?
Barrier method,Surgical,Chemical method.
8. Describe double fertilization in Angiospermic plants.
i)Pollen grains absorb water & nutrients after falling over stigma & forms pollen tube.
ii)Pollen tube grows through the length of style & reaches the ovary.
iii)Pollen tube contains two male gametes.Pollen tube enters the ovule through
micropyle and release its two male gametes
iv)One male gamete fuses with egg to form diploid zygote which later on grow into
embryo.The second male gamete fuses with two polar nuclei.This is called triple fusion
Since two fusions occur in the ovary.Therefore it is called double fertilization.
9)Define the following terms:
a)Fertilisation b)implantation c)placenta d)gestation
a)Fertilisation:The union of male gamete with female gamete to form diploid zygote is
called fertilization.
b)Implantation:Fixation of young embryo in the wall of uterus
c)Placenta:It is a spongy vascular structure formed by maternal & foetal Tissues in the
wall of uterus which is meant for nourishment & waste disposal.
d)Gestation:It is a period btn. Conception & birth of live young ones in mammals.
10.What is pollination.Name its two types.
The transfer of pollen from anther to the stigma of a flower is called pollination.Their are
two types of pollinations: self & cross.
11.Name three methods of propagation.
Cutting, layering & grafting
12.Diagrams:
a)Human female reproductive system
b)Fertilization in flowering plant
c)Binnary fission in amoeba
d)Parts of a bisexual flower
CHAPTER 9 . HEREDITY & EVOLUTION
1.Define the terms: Analogous ,Homologus & Vestigial organs
a) Analogous organs: They are organs which have a different origin and basic plan but
perform different functions .eg.wing of inscets & birds
b) Homologus organs:They are those organs which have similar basic pattern but may
have become different externally .eg. Fore limbs of frog ,lizard ,bird & human.
Genetics : Branch of science that deals with Heredity and variation.
Heredity : It means the transmission of features/ characters/ traits from one generation to
the next generation.
Variation : The differences among the individuals of a species/ population are
called variations
Mendels Experiments : Mendel conducted a series of experiments in which he crossed the
pollinated plants to study one character (at a time)
Monohybrid Cross :
Cross between two pea plants with one pair (monohybrid cross) contrasting characters
Example : Tall / Short Plants.
PARENT
GENERATION
Dwarf plant
Tall plant

TT
tt
T
T
GAMETES
Tt
All tall plants
F1 GENERATION
(first filal generation)
SELF POLLINATION
Tt
Tt
(F1) Tt
(F1)
GAMETES
t
TT
F2 GENERATION
(Second Final
TALL
Gneration
Phenotypic ratio
Phenotypic ratio
Tt
Tt
tt
TALL
TALL
SHORT
3:1
1:2:1
T
Acquired and Inherited Traits
1.
2.
3.
Acquired Traits
These are the traits which are
developed in an individual due
to special conditions
They cannot be transferred to
the progeny
They cannot direct evolution
eg. Low weight of starving
beetles.
1.
2.
3.
Inherited Traits
These are the traits which are
passed from one generation to
the next.
They get transferred to the
progeny.
They are helpful in evolution.
eg. Colour of eyes and hair
Speciation
Micro evolution : It is the evolution which is on a small scale. eg. change in
body colour of beetles.
Speciation : it is the process of formation of new species.
Species : A group of similar individuals that along to a population that can
interbreed and produce ferrite off spring.
Geneflow : It is exchange of genetic material by interbreeding between
populations of same species or individuals
WAYS BY WHICH SPECIATION TAKES PLACE
Speciation takes place when variation is combined with geographical isolation.
Gene flow : occurs between population that are partly but not completely
seperated
Interbreeding
Sub Population
X1 (local)
[Reproduction]
Gene
flow
Variation
in
Local
population
Sub Population
X1
(migrant)
Genetic Drift
It is the random change in the frequency of alleles (gene pair) in a population
over successive generations.
*Natural Selection : The process by which nature selects and consolidate those
organisms which are more suitably adapted and posses favorable variations
I.
Homologous Organs : (Morphological and anatomical evidences. These
are the organs that have same basic structural plan and origin but different
functions.
Example :
Forelimb of Horse
Winds of bat
Paw of a cat
(Running)
(flying)
(walk/scratch/attack)
Same basic
plan,
different
functions
II. Analogous Organs : These are the organs that have different origin and
structural plan but same function example :
Design
different Wings of bat elongated fingers with skin folds same
function
ie. flight
Wings of bird Feather covering along the arm
III. Fossils : (Palaeontological evidences)
The remains and relics of dead organisms of the
past. Example :
i) Fossil of wooly mammoth
ii) Archeopteryx (fossil bird)
iii) Dead insect caught in hot mud.
FOSSILS ARE PRESERVED TRACES OF LIVING ORGANISMS
Eg. AMMONITE
-
Fossil invertebrate
TRILOBITE
-
Fossil in vertebrate
KNIGHTIA
-
Fossil fish
RAJASAURUS
-
Fossil dinosaur skull
CHAPTER -
15
OUR ENVIRONMENT
1MARK QUESTIONS
Q1. What is meant by ‘biodiversity hot spot’?
ANS. It is a biogeographic region which is a significant reservoir of biodiversity.
Q2.what can one of the main objective of biodiversity?
ANS. The main aim of conservation is to try and preserve the biodiversity that we have inherited.
Q3.What may happen if there is a loss of biodiversity?
ANS. The loss of biodiversity may lead to a loss of ecological stability.
Q4.Why do we seek to build dams?
ANS. Large dams can ensure the storage of adequate water not just for irrigation but also for
generation electricity.
Q5.Why should resource like forests, wildlife and water be used in a sustainable manner ?
ANS. Thiscan meet our needs perpetually if we were to use them in a sustainable manner.
2 MARKS QUESTION
Q1. What is ‘Chipko Movement’? Why should we conserve forest?
ANS.The movement started in reni village in Garhwal to protectthe trees by hugging them and not
allowing cutting of these trees is called Chipko Movement. We should conserve forest:
(a)
(b)
(c)
(d)
To maintain ecological balance.
To conserve biodiversity.
To meet our material aspirations.
To prevent global warming.
Q2 What is a biodegradable waste? If all the waste we generatw is biodegradable ,what impact may
this have on the enviorment?
Ans.Biodegradable waste can easily be broken down into non- poisonous simplest substances by
physical;chemical and biological processes
If all waste we generate is biodegradable, it will have little impact on the
environment as most of the waste is decomposed by decomposers and nutrients will be released back
into the nutrient pool
? Q.3What are fossil fuels?Give two examples
A.Fossil fuels are the non renewable fuels formed due to burying of plants and animals under
sedimentary layers of earth, snow or oil millions of years ago.e.g. coal and petroleum
Q.4 Give four ways which show your enviorment friendliness?
A.1 Taking abus instead of using personal vehicle.
2. Using flouorescent tubes instead of bulbs.
3. Using stairs instead of lift.
4. Wearing an extra sweater instead of using a heating device on cold days.
5. Using hanky instead of tissue paper.
Q5. List any four measures for conserving forests?
ANS. Four measures to conserve forest are:
(a)
(b)
(c)
(d)
Afforestation : It is the practice of growing more trees for various purpose.
Preventing Mismanagement : Forest and their resource should not be over-exploited and
its equitable distribution should be ensured.
People’s Participation : People should be given a stake in regulating the forests because
they manage the forest more efficiently.
Tourisms : It should be increased at the expense of the ecology and government should
check whether tourism is damaging the forest or not.
(1)
CHAPTER- 16
NATURAL RESOURCES
Q1
Define natural resources and name any two ?
Q2.
What are renewable and non renewable natural resources.
Q3.
What is deforestation ?
Give two examples each ?
Give consequences of deforestation ?
Q4.
What is afforestation ?
Q5.
Who initiatedChipko Movement?
Q6.
Write expanded forms of IUCN, CITES, IBWL, MAB ?
Q7.
What is water harvesting ?
advantages ?
Q8.
What is meant by three Rs. How should these be followed ?
Q9.
Name any two energy resources which will be exhausted in the future.
alternatives ?
Q10.
What is the significance of Pink and Green pages in Red Data Book ?
Q11.
Suggest a few measures for controlling CO2 is the atmosphere ?
Q12.
Prepare a list of five activities that you perform daily in which natural resources can
be conserved or energy utilization can be minimized ?
What is its slogan ?
mention any two water harvesting structures.
List its four
Suggest
ANSWERS
Ans1.
Natural resources are those living or non-living substances available in the
normal environment which are being exploited for supporting life and meeting
human requirements. E.g. Land, Soil, Water, and Forest etc.
Ans2.
i)
Renewable / inexhaustible natural resources :- These resources occur in
abundance , they are not likely to be exhausted by human use. E.g. Air, Water,
Solar Energy etc.
ii)
Non-renewable / Exhaustible natural resources :- These resources are likely
to get finished due to continuous human use. E.g.Fossils Fuels, Minerals.
Ans3.
Deforestation :The indiscriminate cutting of forest cover due to inhuman
reasons leads to deforestation.
Concequences:1.
2.
3.
4.
5.
6.
Global Warming
Soil Erosion
Droughts
Floods
Landslides
Disturbance in rainfall patterns
Ans4.
Afforestation :available land.
plantation of more and more plants to develop forests in all
Ans5.
ShriSundarLalBahuguna. The slogan of Chipko Movement is five F5 - food,
fodder, fuel, fibre and fertilizer.
Ans6.
IUCN :-
International Union for Conservation of Nature and Natural Resources.
CITES :- Convention on International Trade in Endangered Specious.
Ans7.
IBWL :-
Indian Board of Wild Life.
MAB :-
Man and Biosphere.
Water harvesting is a practice of colliecting rain water in safe storage places
from where it can be used throughout the year both for drinking and irrigation .
The two harvesting structures are :i. Khadin System in Rajasthan.
ii. Kulhs in Himachal Pradesh.
Advantages :i.
ii.
iii.
iv.
Ans8.
It makes rain water percolate slowly underground and recharge ground water.
Harvested rain water can be used for irrigation .
Harvested water can be used for drinking by cattle.
Harvested water provides moisture for crops nearby.
Three ‘R’ are - Reduce, Recycle, Reuse.
Reduce - Minimise the use of natural resources in order to conserve
them.
Recycle - Collect the used and discarded articles such as papers, plastics, glass,
metals etc and send them for recycling to be reused.
Reuse - To reuse again and again like paper, Plastic etc.
Ans9.
Coal and petroleum have a limited stock and hence these will be exhausted in
future . The alternative are :-
i. Use of biogas
ii. Hydropower
iii. Cultivation of petro Plants.
Ans10.
Pink page are meant for critically endangered species and green pages enter
those species that are recovered and deleted from pink pages.
Ans11. i.
Planting of trees
ii. Increased use of alternative sources of evergy instead of fossil fuels.
iii. Avoid burning of litter and crop residue, instead, convert these into
manure.
iv. Smoke from factories should be treated to remove harmful gases before its
discharge into the atmosphere.
Ans12.
i.
Use of fans and lights only when required .
ii. Use CFL in place of conventional electric bulbs / tubes .
iii. Use solar cookers and solar water heating devices instead of using fossil
fuels.
iv. Close taps after use
v. Avoid use of hose pipe for watering plants.
Chapter- 7
CONTROL AND C O-ORDINATION
.1. How many pairs of spinal nerves arise from the spinal cord?
31 pairs
2.What is the functions of hormone secreted by endocrine gland, pituitary?
Pituitary secretes growth hormone.
3.Name two tissues that provide control and co ordination in multicellular animals.
a .Nervous tissues b .Endocrine tissues
4.What is meant by synpses?
Synapse is the functional junction between two neurons.
5.What is meant by tropism?
The movement of a plant in the direction of stimulus is known as tropism.
6. Define reflex action.
Reflex action is a sudden ,involuntary,spontaneous response to the stimuli that is manually to protect
ourselves from any kind of harm.
7.Name the hormone associated with puberty changes in malesand females.
Testosterones(males) ,Estrogen (female)
8.Which part of the brain maintains posture and equilibrium of the body?
Cerebellum.
9.What the function of medulla oblongata ?
Regulating centre for swallowing, coughing,vomiting.
10.Name the largest cell present in human body?
Nerve cell
11.Mention the function of hind brain in human.
It controls ;- salivation,blood pressure,vomiting, maintaining body posture and balance
2 marks questions;-
1.What are the significance of reflex actions?
Reflex actions are very significant because:
I)
II)
They are spontaneous in response to any harmful stimuli,protecting one selves from harm.
These relieve the burden of brain by automatically responding to stimuli.
3.Name the hormone secreted by human testes . state its functions.
a. Testosterones
b.Functions;- it is responsible for the formation of sperms,it casuses changes in the appearances of
body at the age of puberty.
4.What are hormones ? name the hormone secreted by thyroid and state its functions.
Hormones are the chemicals messenger which regulate various metabolic activites.
Hormone secreted by thyroid is thyroxin, function of thyroxin is to regutate various metabolic of
carbohydrates, protein, and fat .
5.What is difference between reflex action and walking?
Reflex action is sudden, unconscious,involuntary response to something in environment while walking
is not unconscious action ,it is a voluntary action which is controlled by human brain. Reflex action is
controlled by spinal cord.
3 marks questions;1.Draw the structure of a neuron and label the following
Nucleus,dendrites cell body ,axon.
2.What are different types of neurons?
There are main three types of neurons;Sensory neuron,motor neuron,connector.
3.What are different types of phytohormones?
Photohormones are hormones secreted by plants for their growth .
a.
b.
c.
d.
Auxin
Gibberellins
Ethane.
Cytokinines.
CH:2
ACIDS, BASES AND SALTS
Some Naturally occuring acids
Vinegar – Acetic Acid
Orange – Citric Acid
Lemon – Citric Acid
Tamarind – Tartaric Acid
Tomato – Oxalic Acid
Sour milk (Curd) – Lactic Acid
Ant and Nettle sting – Methanoic Acid
PROPERTIES:
Acids
– Sour in taste
– Change the blue litmus to red
– eg., HCl , H2SO4, HNO3, CH3 COOH
Bases
– Bitter in taste
– Change red litmus to blue
eg. NaOH, KOH, Ca(OH)2, NH4OH
Acid – Base Indicators – Indicate the presence of an acid or base in a
solution.
 Litmus solution – It is a natural indicator. It is a purple dye extracted from
Lichens.
 Other examples are Red Cabbage and coloured petals of Petunia
and turmeric.
 Olfactory indicators – Show odour changes in acidic or basic media. eg.
onion and clove.
Chemical Properties of Acids and Bases
Acid + Metal Salt + Hydrogen




2HCl + Zn ZnCl2 + H2
2HNO3 + Zn Zn (NO3)2 + H2
H2SO4 + Zn ZnSO4 + H2
2CH3COOH + Zn (CH3COO)2 Zn + H2
Base + Metal Salt + Hydrogen

NaOH + Zn Na2ZnO2 + H2
Action of Acids with metal Carbonates and metal bicarbonates
Metal Carbonate + Acid Salt + Carbondioxide + Water
Na2CO3(s)
+ 2HCl(aq) 2NaCl(aq) + H2O(l) + CO2(g)
Metal bicarbonate + Acid Salt + Carbondioxide + Water
NaHCO3 + HCl NaCl + CO2 + H2O
Lime water Test : On passing the CO2 gas evolved through lime water,
Ca(OH)2 (aq) + CO2(g) CaCO3(s)
+
H2O(l)
Lime water
White precipitate
On passing excess CO2 the following reaction takes place:
CaCO3(s) + H2O(l) + CO2(g) Ca(HCO3)2 aq
Soluble in water
Neutralisation Reactions
Base + Acid Salt + Water
NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
eg., HCl + NaOH aCl + H2O
Reactions of metal oxides with acids
Metal Oxide + Acid Salt + Water
CuO + HCl CuCl2 + H2O
Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base Salt + Water
Ca(OH)2 + CO2 CaCO3 + H2O
– Glowing of bulb indicates that there is a flow of electric current through the
solution.
Alkalis
All bases do not dissolve in water.
An alkali is a base that dissolves in water.
Common alkalis are:
 NaOH Sodium hydroxide
 KOH Potassium hydroxide
 Ca(OH)2 Calcium hydroxide
 NH4OH :Ammonium hydroxide
Note : All alkalis are bases but all bases are not alkalis.
When an acid or a base is mixed with water they become dilute. This results
in the decrease in the concentration of H3O+ or OH– per unit volume in acids
and bases respectively.
Strength of an Acid or Base
Strength of acids and bases depends on the no. of H+ ions and OH– ions
produced respectively.
With the help of a universal indicator we can find the strength of an acid or
base. This indicator is called pH scale.
pH = Potenz in German means power.
This scale measures from 0 (very acidic) to 14 (very alkaline)
7 Neutral (water is Neutral).
pH paper : Is a paper which is used for measuring PH.
 Variation of PH
S. No. PH Value
Colour of the Paper
1.
0
Dark red
2.
4
Orange or yellow
Nature of Solution H+ ion Conc. OH-ion
Highly acidic
very high
very low
Acidic
high
low
.
3.
7:
Green
Neutral
4.
10
Bluish green or blue
Alkaline
5.
14
Dark blue or violet
highly basic
– strongAcids give rise to more H+ions.
eg. HCl, H2SO4 and HNO3.
– Weak Acids give rise to less H+ ions
eg. CH3 COOH, H2 CO3 (Carbonic acid)
– Strong Bases – Strong bases give rise to more OH– ions.
eg. NaOH, KOH, Ca(OH)2
– Weak Bases : give rise to less OH– ions.
eg. NH4OH
Equal
Equal
low
very low
high
very high
More about Salts
Salts and their derivation
S. No. Name of Salt
Formula
Derived from
1.
Potassium Sulphate K2SO4
KOH +H2SO4
2.
SodiumSulphate
Na2SO4
NaOH+ H2SO4
3.
SodiumChloride
NaCl
NaOH+ HCl
4.
AmmoniumChloride NH4Cl
NH4OH+ HCl
Note : NaCl and Na2 SO4 belong to the family of sodium salts as they have
the same radicals. Similarly NaCl and KCl belong to the family of chloride
salts.
Importance of pH in our daily life
 Importance of pH in our digestive system – pH level of our body regulates
our digestive system. In case of indigestion our stomach produces acid in a
very large quantity because of which we feel pain and irritation in our stomach.
To get relief from this pain antacids are used. These antacids neutralises the
excess acid and we get relief.
 pH of Acid Rain : When pH of rain water is less than 5.6 it is called Acid
Rain.When this acidic rain flows into rivers these also get acidic, which causes
a threat to the survival of aquatic life.
 pH of Soil : Plants require a specific range of pH for their healthy growth. If
pH of soil of any particular place is less or more than normal than the farmers
add suitable fertilizers to it.
 Our body functions between the range of 7.0 to 7.8
 Tooth decay and pH : Bacteria present in the mouth produce acids by
degredation of sugar and food particles remaining in the mouth. Using toothpaste
which is generally basic can neutralise the excess acid and prevent tooth
decay.
 Bee sting or Nettle sting contains methanoic acid which causes pain and
irritation. When we use a weak base like baking soda on it, we get relief.
Chemicals from Common Salt
– Sodium chloride is called as common salt used in our food. It is derived
from seawater.
– Rock Salt is the brown coloured large crystals. This s mined like coal.
– Common Salt is an important raw material for many materials of daily use
such as.
Sodiumhydroxide
Washing Soda
Bleaching Powder.
SodiumHydroxide
Preparation : Prepared by the method called chlor-alkali
Called chlor-alkali because we get chlorine and a base in this.
2NaCl(aq) + 2H2O(l) 2NaOH(aq) + Cl2(g) + H2(g)
Bleaching Powder
Preparation Ca(OH)2 +
calcium hydroxide
Cl2 CaOCl2 + H2O
chlorine
bleaching water
uses in textile, factories and laundry, used as disinfectant
Baking Soda
– Common name – Sodium Hydrogen Carbonate
Preparation NaCl + H2O + CO2 + NH3 NH4Cl + NaHCO3
On heating NaHCO3 produces :
NaHCO3 HeatNa2CO3 + H2O + CO2
CO2 produced causes dough to rise and make cakes, pastries spongy.
Uses : In household, ingredients of antacid
In making baking power
On heating baking powder produces
NaHCO3 + H+ CO2 + H2O + Sodium Salt of acid
Washing Soda
Preparation : Recrystallisation of sodium carbonate
Na2CO3 + 10H2O HeatNa2CO3. 10H2O
Uses
– Used in glass, soap and paper industry
– Cleaning agent for domestic purposes.
– Removal of hardness of water.
– Manufacturere of borax.
Water of crystallisation : Fixed no. of water molecules present in one formula
unit of a salt.
– On heating copper sulphate crystals water droplets appear, formula of
hydrated copper sulphate – CuSO4. 5H2O.
– gypsum also contains water of crystallisation.
– Formula of gypsum – CaSO4.2H2O
– On heating gypsum at 373k it becomes CaSO4.½H2O is plaster of
paris.
– Plaster of Paris is used as plaster for fractured bones.
– When plaster of Paris is mixed with water it changes to gypsum.
CaSO4.½ H2O + 1½ H2O CaSO4.2H2O
Uses of plaster of Paris :Making toys, decorativematerial and smooth surfaces.
CH: 4. CARBON AND ITS COMPOUNDS
BONDING IN CARBON---- THE COVALENT BOND
CARBON - ATOMIC NUMBER IS--- 6
ELECTRONIC CONFIGURATION--- 2, 4
Carbon needs four electrons to attain noble gas configuration.
1) If it were to lose four electrons forming C4- anion. But nucleus with 6 protons cannot hold on to ten
electrons.
2) It could lose four electrons forming C4+ cation. But it would require a large amount of energy to
remove 4 electrons .
Carbon overcomes this by sharing its valence electrons with atoms of carbon or with atoms of other
elements.
COVALENT BOND
The bond formed by sharing of electrons between two atoms so that both can achieve a completely
filled outermost shell.
covalent
bond
single
double
tripple
covalent bond
covalent bond
covalent bond
SINGLE BOND
2
DOUBLE BOND
2
TRIPLE BOND
2
AMMONIA
 Covalently bonded molecules have strong bonds within the molecule, but
intermolecular forces are small. This gives rise to low melting and boiling
point.
CO2
VERSATILE NATURE OF CARBON
The versatile nature of carbon is due to two factors:
1) CATENATION
2) TETRAVALENCY
CATENATION: The unique ability of carbon to bond with other atoms of carbon, giving rise to large
molecules.
TETRAVALENCY: Carbon has valency four so it is capable of bonding with four other atoms of carbon
or other atoms of monovalent element.
CARBON
COMPOUNDS
SATURATED
SATURATEDCOMPOUNDS
UNSATURATED
UNSATURATED COMPOUNDS
These are linked by single bond between the
carbon atoms.
These are linked by double or triple bond
between carbon atoms.
Not very reactive
Very reactive
stable
unstable
Example: Alkane (CnH2n+2)
Example: Alkene (CnH2n)
Alkyne (CnH2n-2)
FORMULAE AND STRUCTURES OF ALKANES

STRUCTURAL ISOMERS
Compounds with same molecular formula but different structures are called STRUCTURAL ISOMERS.
eg. ISOMERS OF PENTANE
ISOMERS OF HEXANE
CYCLIC CARBON COMPOUNDS
eg. CYCLOPENTANE
CYCLOHEXANE
BENZENE
FUNCTIONAL GROUPS
An atom or group of atoms present in a molecule which largely determines its chemical properties.
ORGANIC FUNCTIONAL GROUPS
NAME
1) ALCOHOL
2) ALDEHYDE
FUNCTIONOL ENDING
GROUP
|
—C—O—H
-ol
|
—C=O
H
|
-al
3) ACID
O
||
—C—O—H
-oic acid
4) KETONE
O
||
R—C—R
-one
HOMOLOGOUS SERIES
A family of organic compounds having the same functional group, similar chemical properties and
each member differs by –CH2 unit.
1. ALKANE -CnH2n+2
CHARACTERISTICS OF HOMOLOGOUS SERIES
1) All members of a homologous series can be represented by a general formula example Alkane—
CnH2n+2.
2) The molecular formula of any two successive members differ by- CH2 UNIT.
3) The molecular masses of any two successive members differ by 14 ꜡.
4)All members of a series have same functional group.
5) All members of a series show similar chemical properties.
ALKANES
Alkenes
SOAPS AND DETERGENTS
Definition: Any substance which has cleansing action in water is called a Detergent.
DETERGENT
1. Soapy – Soaps
2. Non-Soapy – Detergents
SOAPS
A soap is a Sodium Salt (potassium salt) of a long chain Carboxylic acid which has cleansing
properties in water.
A soap molecule has two ends:a. A large non - ionic hydrocarbon end
b. An ionic end, COO -Na+
Examples:
i.
Sodium Stearate, C17H35COO-Na+
ii.
Sodium Palmitate, C15H31COO-Na+
MANUFACTURE OF SOAP
A soap is made by heating animal fat or vegetable oil, with concentrated sodium hydroxide
solution. The fats or oils react with sodium hydroxide to form Soap and Glycerol:
Fat or Oil + Sodium Hydroxide ------- Soap +Glycerol
The process of making soap by the hydrolysis of fats and oils with alkalis is called
Saponification.
Note:
Vegetable oils like Caster oil, Cotton seed oil, Coconut oil etc are also used for
preparing soaps.
The other major soapmaking process is the neutralization of fatty acids with an alkali. Fats and oils are
hydrolyzed (split) with a high-pressure steam to yield crude fatty acids and glycerine. The fatty acids
are then purified by distillation and neutralized with an alkali to produce soap and water (neat soap).
When the alkali is sodium hydroxide, a sodium soap is formed. Sodium soaps are "hard" soaps. When
the alkali is potassium hydroxide, a potassium soap is formed.
Potassium soaps are softer and are found in some liquid hand soaps and shaving creams.
The carboxylate end of the soap molecule is attracted to water. It is called the hydrophilic (waterloving) end. The hydrocarbon chain is attracted to oil and grease and repelled by water. It is known as
the hydrophobic (water-hating) end.
STRUCTURE OF SOAP
A soap molecule has two parts:
a. A long hydrocarbon end
b. A short ionic end-COO-Na+
A long hydrocarbon chain is hydrophobic (Water Repelling).
The ionic part is hydrophilic (Water Attracting).
Note: The hydrocarbon part of the soap molecule is soluble in oil or grease, so it can attach
to the oil or grease particles present on dirty clothes.
The short ionic part of the soap molecule is soluble in water, so it can attach to the water
particles
CLEANSING ACTION OF SOAP
1. A dirty cloth is put in water containing dissolved soap,
2. Soap molecules arrange themselves radially along the dirt in such a manner that the
hydrocarbon ends of the soap attach to the dirt and the ionic ends remain attached to
water. This is called Micelles.
3. When dirty cloth is agitated in soap solution, the dirt present on its surface and entrapped
by soap micelles get dispersed in water due to which soap water becomes dirty but the
cloth gets cleaned.
4. The cloth is cleaned thoroughly by rinsing in clean water.
DETERGENTS (NON-SOAPY)
A detergent is the sodium salt of a long chain Benzene sulphonic acid which has cleansing
properties in water. They are used for making shampoos and washing Powders.
Differences between Soaps and Detergents
SOAPS
DETERGENTS
Sodium salts( potassium salt) of long Sodium salts of long chain benzene
chain carboxylic acids.
sulphonic acids.
Do not give lather with hard water.
Give lather with hard water.
Biodegradable.
Non-Biodegradable
Advantages of Detergents over Soaps
1. Detergents can be used in hard water.
2. Detergents have stronger cleansing action than soaps.
3. Detergents are more soluble in water than soaps.
Disadvantage of Detergents over Soaps
1. Detergents are non- biodegradable.
CH:1. CHEMICAL REACTIONS AND EQUATIONS
What are chemical reactions?
Chemical Reactions involve the breaking and making of bonds between atoms to
produce new substances.
Types of Chemical Reactions :
1.Combination reaction.(synthesis reaction.)
i. Mg +O2
MgO
ii. C + O2
CO2
iii. 2H2 +O2
2H2O
2. Decomposition reaction.
i. CaCO3
heat
ii. FeSO4
heat
CaO + CO2
Fe2O3 +SO2 +SO3
3. Displacement reaction.
i. Fe + CuSO4
FeSO4 +Cu.
ii. Pb + CuCl2
PbCl2 + Cu.
4. Double displacement reaction.
i. Na2SO4 +BaCl2
BaSO4 + 2NaCl.
ii. NaCl +AgNO3
NaNO3 + AgCl
5. Oxidation and reduction reaction (Redox)
OXIDATION
2CuO + H2
2Cu + H2O
REDUCTION
CORROSION: An oxidation reaction which causes rusting of iron.
Definition:
Attacking of metals by surrounding substances
air,moisture,acids. For eg. Rusting of iron,a green coating on copper,
a black coating on silver.
like
RANCIDITY: Changing of the taste and smell of fatty foods due to oxidation
of fats is called Rancidity.
Methods to prevent Rancidity:
Keep food in air tight containers.
Add antioxidants to the food.
Flush the packed foods with gases like nitrogen.
CHEMICAL REACTIONS AND EQUATIONS
(BALANCING OF EQUATIONS)
Chemical Equation:
Chemical Equation represents a chemical reaction symbolically.
Mg
+
O2
MgO
(Reactants)
(Product)
Balanced Chemical Equation
A Chemical Equation is said to be balanced when the number of atoms of each element
remains the same before and after a Chemical Reaction.
IMPORTANCE OF PH IN EVERYDAY LIFE
What is pH?pH is a number which indicates the acidic and basic nature of a solution.
Higher the hydronium ion concentration, lower is the pH
‘p’ stands for ‘potenz’. It means power of hydrogen ions in the solution.
pH of neutral solution is 7.
pH of acidic solution is less than 7.
pH of basic solution is more than 7.
IMPORTANCE OF pH IN EVERYDAY LIFE
pH RANGE FOR WORKING OF OUR BODY:--------------- 7.0 to 7.8
pH in our digestive system




our stomach produces hydrochloric acid (HCl) for digesting food.
If amount of acid is more than required, pH of the stomach is lowered.
As such , it causes acidity (indigestion).
To neutralize the extra acid a base (Antacid) is taken.


Example of Antacids: Mg(OH)2 (Magnesium hydroxide) also known as Milk
ofMagnesia.
Al(OH)3 (Aluminium hydroxide)
pH as the cause of tooth decay


Bacteria in the mouth act on sweet foods and produce acids
This lowers down the pH of the mouth below 5.5 and thus corrode the teeth.
PREVENTION OF TOOTH DECAY
Clean the mouth after eating.
Use toothpastes which are basic in nature.
SELF DEFENCE IN PLANTS AND ANIMALS
I.
II.
Plants like Nettle have stinging hair which produces methanoic acid on being touched.
Rubbing of dock plant neutralizes the acid and thus relieves the pain.
Insects like Wasps and honey bees leave an acid on being stung.
Use of a mild base (NaHCO3) on the stung area relieves the pain.
CH:3. METALS AND NON- METALS
HOW DO METALS AND NON- METALS REACT?
METALS:
SODIUM ATOM
MAGNESIUM ATOM
ALUMINIUM ATOM
These are metals. Let,s have a look at their electronic configuration.
Atom
atomic number
electronic configuration
Na
11
2,8, 1
Mg
12
2,8 , 2
Al
13
2, 8 ,3
Metals have 1 ,2 or 3 electrons in their outermost shell. They attain stable configuration by
losing their valence electrons and and become positive charge- cation.
Now,let,s have a look at the Non- metals.
NON- METALS
ATOM
ATOMIC NUMBER
ELECTRONIC CONFIGURATION
N
7
2,5
O
8
2, 6
Cl
17
2 ,8, 7
Non metals have 5,6 or 7 electrons in their valence electrons. They attain stable configuration
by gaining electrons and become negative charge- anion.
Now , let,s see how metals and non metals react?
Sodium atom
Chlorine atom
+
_
Na+
Cl-
(Electrons=10
(electrons= 18
Protons= 11)
protons=
17)
NaCl
Sodium and Chloride, being oppositely charged, attract each other and are held by strong
electrostatic forces of attraction to exist as Sodium chloride.
NOTE: Sodium chloride exist as aggregates of oppositely charged ions.
FORMATION OF MAGNESIUM CHLORIDE
MgCl2
The Oxidation of Magnesium Metal
Recall from section 4.6, a magnesium atom loses its 2 outer-shell electron to become a
magnesium ion, (i.e. cation ). The magnesium metal is said to be
oxidized
.
3. The Reduction of Chlorine Gas:
Recall from section 4.7, chlorine is a diatomic element. The covalently bonded Cl2
molecule gains two electrons to become two chloride ions, (i.e. anions). Chlorine is
said to be reduced.
2 . Combining the above oxidation and reduction processes, the overall effect
the transfer of TWO electrons is from magnesium to chlorine.
IONIC COMPOUNDS
The compounds formed by transfer of electrons from a metal to a non- metal.
PROPERTIES OF IONIC COMPOUNDS
1) PHYSICAL NATURE: Ionic compounds are solids and hard because of the strong force
of attraction between the positive and negative ions. These are Brittle.
2) MELTING AND BOILING POINTS: Ionic compounds have high melting and
Boiling points because a considerable amount of energy is required to break the strong
interionic attraction.
3) SOLUBILITY: Generally soluble in water and insoluble in solvents like kerosene , petrol
etc.
4) CONDUCTION OF ELECTRICITY: Conducts electricity in molten or aqueous state.
MOLTEN STATE: In molten state, the electrostatic force of attraction between the
oppositely charged ions are overcome by heat. Thus, the ions move freely and conduct
electricity.
AQUEOUS STATE: A solution of an ionic compound in water contains ions,which move to
the opposite electrodes when electricity is passed through the solution.
SOLID STATE: Ionic compounds do not conduct electricity in solid state because movement
of ions in solid is not possible due to their rigid structure.
Physical properties of non-metal
(6) Physical state: - Non Metals are either solid or gasses except Bromine.
(7) Non Metals are dull in lusture except iodine.
(8) Non Metals are soft except carbon.
(9) Non Metals are non-malleable and non-ductile.
(10)
Non Metals are bad conductor of heat and electricity except graphite
which is good conductor of electricity.
Chemical properties of metal
(5) Reaction with air: - Metal + Oxygen
4 Na + O2
(6) Reaction with water: - Metal + Water
→
→
→
Metal Oxide
2 Na2O
Metal Oxide + Hydrogen
Metal Oxide + Water →
2K + 2 H2O
Metal Hydroxide
→
2KOH + H2
(7) Reaction with Acid: - Metal + Acid → Salt + Hydrogen
2Na + 2HCL → 2NaCl + H2
(8) Reaction with salt: - More reactive metal displace less reactive method from
their salt solution.
Example: - Zn + CuSo4 → ZnSo4 + Cu
The arrangement of metals in the order of their decreasing reactivity is known as activity series.
K
Most Reactive
Na
Ca
Mg
Al
Zn
Fe
Reactivity Decreases
Pb
H
Cu
Hg
Ag
Au
Least Reactive
METALLURGY
Various processes involved in the extraction of metal from their ores and then refining them is known
as metallurgy.
Extracting Metals low in the activity series: Metals lows in the activity series are very unreactive . Oxides of these metals can be reduced to
metals by heating alone. eg. Cinnabar (HgS) is an ore of Mercury.
2HgS + 3 O2
2HgO
→
→
2HgO + 2SO2
2Hg + O2
Extracting metal in the middle of the activity series: The metals are usually present as sulphide or carbonate in nature. Sulphide ore are converted into
oxides by heating strongly in the presence of excess air. This process is known as roasting. The
carbonate ore are change into oxides by heating strongly in limited air. This process is known as
calcination.
Roasting: - 2ZnS + 3 O2
Calcination: - ZnCO3
→
→
ZnO + CO2
2ZnO + 2So2
ZnO + C
→
Zn + Co
Beside using carbon (coke) to reduce metal oxide to metals sometime displacement reaction can also
be used.
Displacement reactions are highly exothermic. eg. The reaction
Fe2O3 + 2Al
→
2Fe +Al2O3 + Heat of iron(III) oxide (Fe2O3) with alluminium is used to join
railway tracks or cracked machine parts. This reaction is known as thermic reaction.
Extracting metals towards the top of the activity series: Metals high up in the activity series are very reactive. They can be obtained from their compounds by
heating with carbon. Eg. Na, Mg and Ca are obtained by the electrolysis of their molten chloride.
Metals are deposit at the cathode were as chlorine is liberated at the anode.
At Cathode Na⁺
+ e⁻ → Na
At Anode 2Cl⁻
→ Cl2 + 2e⁻
CORROSION: - Combining of metal with oxygen in air in presence of moisture is known as corrosion.
Methods of preventing corrosion are paint, oiling. Greasing, galvanizing, anodizing, electroplating and
alloying
Chapter 5 :PERIODIC CLASSIFICATION OF
ELEMENTS






Classification and its need
Basis of classification
Dobereiner’s law of Triads
Newland law of Octaves
Mendeleef’s classification
Modern Periodic Table
MODERN PERIODIC TABLE
“Properties of elements are a periodic function of their atomic number.”
POSITION OF ELEMENTS IN THE MODERN PERIODIC TABLE
The modern periodic table has:
18 vertical columns -----------
GROUPS
7 Horizontal rows
PERIODS.
-----------
The number of elements in a period is based on how electrons are filled into various shells.(
2n2)
For example;
K shell---2x(1)2 = 2,hence the first period has 2 elements.
L shell—2x(2)2 = 8, hence the second period has 8 elements.
M shell---2x(3)2 = 18,but the outermost shell can have only 8electrons,so the third period has
only 8 elements.
TRENDS IN THE MODERN PERIODIC TABLE
VALENCE ELECTRONS
Electrons present in the outermost shell or valence shell.
VALENCY
Valency of an element is determined by the number of valence electrons present in the
outerm
Valency of elements in a group
Valency increases from 1 to 4 and decreases to
ost
is same.
0.
shell of
GROUP 1
Li
Be
B
C
N
O
F
Ne
its
H---(1) 1
3
4
5
6
7
8
9
Li----(3) 2 1
10
atom.
Na (11) 2 8 1
2,1
2,2 2,3 2,4 2,5
2,6 2,7
2,8
ATOM
K (19) 2 8 8 1
IC SIZE (radius of an atom):
Distance between the centre of the nucleus and the outermost shell of an isolated
atom.
Elements have same valence
electrons.
GROUP 1
H (1) 1
Li(3) 2 1
Na(11)2 8 1
K( 19) 2 8 8 1
Valence electrons increases as atomic number
Increases.
PERIOD2;
Li
Be
B
C
N
O
F
Ne
3
4
5
6
7
8
9
10
2,1
2,2 2,3 2,4 2,5
2,6 2,7
2,8
At
o
mi
c
ra
diu
s
inc
re
as
es
do
wn
th
e
gr
ou
p
Ato
mic
radi
us
decr
ease
s in
mov
ing
fro
m
left
to
Righ
t
bec
aus
e of
be
ca
us
e
nu
m
be
r
of
sh
ell
s
inc
re
as
e.
METALLIC PROPERTIES
incr
ease
in
nucl
ear
char
ge
Whi
ch
tend
s to
pull
the
elec
tron
s
clos
er
to
the
Nucl
eus.
(Tendency to lose electrons from the valence shell)
Metallic properties increase because
number of shells increases so, effective
nuclear charge decreases.
Metallic properties decrease because
effective nuclear charge increases.
NON – METALLIC PROPERTIES
( Tendency to gain electrons)
Non-metallic properties decreases
because effective nuclear charge
decreases.
Non- metallic properties increases
because
effective nuclear charge increases.
Click Here for Animation
ELEMENT
ATOMIC
ELECTRONIC
SODIUM
NUMBER
CONFIGURATION
Na
11
K
L
M
2
8
1
NUMBER OF SHELLS= PERIOD NUMBER
VALENCE
ELECTRON =
GROUP NUMBER
SODIUM BELONGS TO:
GROUP =
PERIOD =
1
3
Valence electron= 1,
number of shells = 3
Chapter 10
LIGHT `REFLECTION & REFRACTION
1.Reflection and its meaning
2. Laws of Reflection:
: The incident ray, the normal to the surface
at the point of incidence and the reflected ray, all lie in the same
plane.
: The angle of incidence is equal to the
angle of reflection.
3. Real image is obtained when the rays of light after reflection, actually
converge at a point. It can be obtained on the screen and can be seen
with the eye.
4. Virtual image forms when rays of light do not actually meet, but
appear to meet when produced backwards. It cannot be obtained on
the screen.
5. Characteristics of the image formed by the plane mirror:
a. The image formed by a plane mirror is always virtual and erect.
b. Size of image = Size of object and the image is laterally inverted.
c. The image formed by the plane mirror is as far behind the mirror as
the object is in front.
6. A spherical mirror whose reflecting surface is curved outwards and
polished on the inner spherical surface is convex mirror.
7. A spherical mirror whose reflecting surface is curved inwards and
polished on the outer spherical surface is concave mirror.
8. Concave mirror mostly forms real images, which can be received on
the screen.
9. Convex mirror forms virtual images, which cannot be received on the screen.
10. Differentiating between a plane mirror, a concave mirror and a convex
mirror, without touching them:
a. If the image formed is erect and is of same size as in reality then it
is a plane mirror.
b. If the image formed is still erect but smaller in size then it is a
convex mirror.
c. If the image is erect but magnified when mirror is close to the
object then it is a concave mirror.
11. Solar concentrators use huge concave mirrors to focus large amounts
of solar energy thereby producing high temperature conditions in a
solar power plant.
12. Concave mirrors are used as shaving and make up mirrors.
13. The centre of the reflecting surface of a spherical mirror is a point
called the pole of the mirror and usually represented by P.
14. The horizontal line passing through the centre of curvature and pole of
the spherical mirror is known as Principal axis.
15. Centre of curvature of a spherical mirror is the centre of the hollow
sphere of glass, of which the spherical mirror is a part and usually
represented by C.
16. Radius of curvature of a spherical mirror is the radius of the hollow
sphere of glass, of which the spherical mirror is a part and usually
represented by R.
17. The diameter of the reflecting surface that is twice the radius is called
Its aperture.
18. Radius of curvature (R) = 2 × focal length (f)
19. Rules for ray diagrama. The path of the reflected light ray depends upon how the incident
ray is oriented with respect to the principal axis.
b. A ray of light parallel to the principal axis, after reflection pass
through the principal focus.
c. A ray of light passing through the principal focus of a mirror
becomes parallel to the principal axis of the mirror, on reflection
d. A ray of light incident obliquely towards the pole of mirror is
reflected obliquely as per the laws of reflection
e. A ray of light passing through centre of curvature of a mirror is
reflected back along the same path
20. Image formation by a concave mirror for different positions of the object
21. Nature, position and relative size of the image formed by a convex mirror:
22. Cartesian Sign Convention For Spherical Mirrors
23. The ratio of the height of the image(hi) to the height of the object(ho) is
known as the magnification(h1)/ (h0)
24. Magnification is positive for virtual image and negative for real image.
25. Mirror formula: 1/f= 1/v +1/u where f, v and u are the focal length, image distance and object
distance.
26. The phenomenon of change in the path of light from one medium to
another is called refraction of light.
27. The angle formed between the incident ray and the normal is called
angle of incidence and the angle formed between the refracted ray and
the normal is called angle of refraction.
28. The cause of refraction is the change in the speed of light as it goes
from one medium to another medium.
29. Larger the difference in speeds of light, the greater will be the angle of
bending and vice-versa.
30. When a ray of light passes from a rarer medium to a denser medium,
it bends towards the normal. Also, the angle of incidence is greater
than the angle of refraction.
31. When a ray of light passes from a denser medium to a rarer medium,
it bends away from the normal. Also, the angle of incidence is less
than the angle of refraction
32. Laws of refraction:
a. The first law of refraction: The incident ray, the refracted ray and
the normal at the point of incidence all lie in the same plane.
b. Second law of refraction: The ratio of the sine of angle of incidence
in the first medium to the sine of angle of refraction in the second
medium is a constant for a given pair of medium and for a given
wavelength of light.
n=sin i/sin r
where n is a constant known as refractive index of the second
medium with respect to the first medium. This law is also called as
Snell’s Law
33. The phenomenon of change in path of light in going from one medium
to another is called refraction of light.
34. The ratio of speed of light in vacuum to the speed of light in a medium
is called the refractive index of the medium. It has no unit.
35. The shifting of emergent ray sideways from the direction of original
incident ray is called lateral displacement or lateral shift
36. The angle through which a ray of light deviates on passing through a
prism is called the angle of deviation.
37. Convex lens is thicker at the middle than at the edges.
38. Concave lens is thicker at the edges than at the middle.
39. Convex lens converge the rays of light while concave lens diverges.
40. Focal length of convex lens is positive and Concave lens is negative.
41. Nature, position and relative size of the image formed by a convex lens:
42. Nature, position and relative size of the image formed by a concave lens:
43. Lens formula: if u, v and f are the object distance, image distance and focal length respectively
then 1/f=1/v-1/u
44. Power of a lens is the reciprocal of its focal length. The SI unit of
power of a lens is Dioptre, P= 1/f(in meter)
one mark Questions With Answers
Define the following :
i) Ray of light : It is the straight line indicating the path of the light .
ii) Beam of light: It is the bundle of rays originating from the same source of light in a particular
direction .
iii) Parallel beam: It is a pencil in which all the rays move parallel to each other..
iv) Divergent beam: It is a pencil in which all the rays meet at a point when produced backward.
v) Convergent beam: It is a pencil in which width of the pencil goes on decreasing as the rays
proceed forward
vi) Real image: It is the image obtained when the rays of light after reflection, actually converge
at a point.
vii) Virtual image: It is the image obtained when rays of light do not actually meet, but appear to
meet when produced backwards.
1) What type of image is formed by the plane mirror?
Ans Unmagnified, virtual and erect.
2) Define the following terms in relation to concave spherical mirror:
i) Pole: It is the central point of a mirror.
ii) Centre of curvature: It is the centre of the sphere of which mirror is a part.
iii)
Radius of curvature: It is the radius of the sphere of which mirror is a part.
iv)Principal Axis: It is the straight line passing through the pole and centre of curvature of the mirror.
v) Principal Focus: It is a point on the principal axis at which the rays parallel to the principal axis meet
after reflection or seem to come from.
vi)Aperture It is the diameter of the light reflecting surface.
vii)
Focal length: The distance between pole and the focus is called focal length.
3) Name the mirror that gives erect and enlarged image of the object
Ans Concave mirror.
4) What is the SI unit of power?
Ans Dioptre
5) Give the mathematical expression for power of a lens
Ans Power, P=1/f
6) How will you identify a concave mirror by touching it?
Ans A concave mirror is thinner at the centre and thicker at the edges.
7) Which mirror is used by dentists?
Ans Concave mirror
8) Which mirror gives a large field view?
Ans Convex mirror
9) Which mirror is used to obtain a real image?
Ans Concave mirror
10)
Give the mathematical expression for power of a lens
Ans Power, P=1/f
Two mark questions:
1. State Snell’s Law of refraction
Ans The ratio of the sine of angle of incidence in the first medium to the sine of angle of refraction in
the second medium is a constant for a given pair of medium and for a given wavelength of light, n=sin
i/sin r
2 Why does a ray of light bend when it travels from one medium into another?
AnsBecause its velocity changes when it moves from one medium into the other.
3 Which mirror is used in solar furnace and headlights of car?
Ans Concave mirror
4 Write Lens Formula
Ans1/f=1/v-1/u
5 What is the other name of convex lens?
Ans Converging lens
6 The image formed by a lens is always erect and diminished. What is the nature of the lens?
Ans Concave lens.
7 Where will the image be formed by concave mirror when an object is placed between pole and the
focus point of the mirror?
Ans: Behind the concave mirror.
8 What is the value of focal length of a plane mirror?
Ans: Infinity.
9 What type of lens does a drop of water behave like?
Ans: Convex lens.
10
The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
Ans. we know that f = R/2
So, f = 20/2 = 10 cm
11 What is the power of the convex lens of focal length 25 cm?
Ans Focal length, f = 25cm =0.25 m
Using, P= 1/f =1/-0.25 = -4 D
Three marks questions:
1. Define Pole. . should an object be placed on the principal axis of a concave mirror so that its
real image is of the same sizeas that of the object is formed?. Name the mirror which acts as a
convergent mirror
i) It is the central point of a mirror.
ii) Object must be placed between the pole and focus of the concave mirror.
iii) concave mirror
2. A Spherical mirror in which reflecting surface is towards the Centre of the sphere of which the
mirror is a part, is called concave mirror, i.e., reflection of light for this mirroroccurs at concave
surface or bent-in surface.
The rays of light incident on concave mirror in a direct parallel to the principal axis, actually meet at a
single point F on the principal axis of the mirror. This point is called principal focus of the mirror.
I)Is principal focus of a concave mirror, a real point or a virtual point?
II)What happens in case of a convex mirror?
III)Our teachers and parents advise us to stay Focused. What does it imply?
ANS I)The principal focus F of a concave mirror is a real point. This is because the rays of
light, on reflection from the mirror meet actually at F.
II)In case if a convex mirror, reflection of light occurs at convex surface or the bulged out
surface. Principal focus F in this case is a virtual point, as reflected rays only appears to
come from F.
iii)Our parents and teachers advise us to stay focused. It implies that we concentrates all
our energies at a single point/problem so that we can resolve the same easily. Staying
focused means we do not divert our energies and attention to several things at a time. This
would lead us nowhere. Hence, the secret of success is to stay focused.
3)In case of both, convex mirror and concave mirror, any line passing through centre of
curvature of the mirror is normal to the mirror. A ray of light falling normally on the mirror,
retraces its path on reflection. This is because for a normal ray, angle of incidence, ∟ i = 0˚.
As angle of reflection is equal to angle of incidence, i.e., ∟r = ∟i, therefore, ∟r = 0˚. That is
why the path of the ray falling normally on the mirror is retraced.
3. Read the above passage and answer the following questions:
I)Do the rays passing through principal focus of mirror fall normally on the mirror?
II)Which is closer to the mirror, principal focus or centre of curvature of the mirror?
III)What values of life do you learn from this concept?
ANS: I)No, the rays passing through principal focus of mirror do not fall normally on the
mirror.
II) principle focus F of the mirror is closer to the pole P of the mirror, compared to the
centre of curvature , C.
Infact ,PF = ⅟2PC.
III)This concept implies that one should preferably stay along normal to avoid deflections.
Staying in normal mod will save you from large scale fluctuations. They say, too much of
everything is bad. So eat normal, sleep normal, play normal, study normal, talk normal,
listen normal and so on. Prefer not to do anything abnormally.
4.Power of a lens is a measure of the ability of the lens to converge the rays of light falling
on it. Quantitatively, power of a lens = reciprocal of focal length of lens, i.e., P = ⅟f. if a lens
happens to diverge the rays of light falling on it, its power is said to be negative. Thus ,
power of a convex lens is positive and power of a concave lens is negative.
If P₁, P₂ are powers of two lenses held in contact with each other, the power of the combination is
P = P₁ +P₂. Note that P₁, P₂ are to be added with proper sign.
Read the above passage and answer the following questions:
(i)
(ii)
(iii)
What is the SI unit of power?
Focal length of a concave lens is 20 cm. What is its power?
What lessons of life do you learn from the relation P =P₁+P₂?
Ans.
(i)
(ii)
SI unit of power is diopter (D). 1 diopter is the power of a lens of focal length one metre.
Here, f = -20 cm = -20/100 m = -1/5 m. P =⅟f = ⅟-₁/5 = -5D
(iii)
If P₁=3D and P₂=-2D, then
P=P₁+P₂ =3D -2D=1D
Again, if P₁=3D and P₂ =2D, then
P=P₁+P₂=3D+2D=5D
i.e., power of combination is much larger when the two lenses are of same nature. The
same is true in real life. To make a powerful combination in business, partners should
preferably be of same nature. Same is true for life partners, i.e., husband and wife. If their
nature is identical, they will make an adorable couple
Chapter 11
Human eye and the colorful world
Multiple choice questions: (one mark questions)
1.The human eye forms its image at it’s
a)
b)
c)
d)
cornea
iris
retina
pupil
2. Least distance of distinct vision of a normal human eye of an adult is:
a) 25mm
b) 25 cm
c) 25m
d)none of these
3.The change in the focal length of an eye lens is caused by the action of the
a) pupil b) iris c) ciliary muscle d) retina
4. The focal length of an eye lens is controlled by
a) pupil b) iris c) ciliary muscle d) optic nerve
5.A white light is fall on the glass prism. The least deviated colour is
a) red b)yellow,
c)green
d)violet
6.Blue colour of sky is due to
a) dispersion b) scattering c) diffraction d) polarisation
7. Outer layer of human eye is:
a) retina b) scelerotic c) choroid d)none of these
8. The si unit of power of a lense is
a) ampere b) dipotre c) ohm d) none of these
9. Blind spot is formed on
a)retina b) pupil c) optic nerve d) none of these
10. A person is not able to see far way object clearly is suffering from
a) Hypermetropia b) myopia
c) cataract d) presbyopia
ANSWER
1.C
2.b
3.c
4.c
5.a
6.a
7. b
8. b
9. c
10. b
HUMAN EYE AND THE COLOURFUL WORLD
MINIMUM LEARNING PACKAGE
SECTION A (1 MARK)
1) What are near point and far point of a normal eye?
Ans Near point = 25 cm and far point = infinity
2) What is the least distance of distinct vision of a mormal eye?
Ans 25 cm
3) What is dispersion?
Ans the splitting of white light into seven different colours on passing through prism is called
dispersion.
4) A person is advised to wear spectacles with concave lenses. What type of defect of vision is he
suffering from?
Ans Myopia
5) Name the phenomena responsible for twinkling of stars .
Ans Atmospheric refraction.
6) Where does human eye forms the image of an object?
Ans Retina
7) Which lens is used for correction of hypermertopia?
Ans Convex lens
8) Which part of human eye controls the amount of light entering the human eye?
Ans Iris
9) A child is sitting in the classroom is not able to read the blackboard clearly. Name the type of
defect from which the eye is suffering.
Ans Myopia or short –sightedness
10) Define spectrum.
Ans The pattern of seven colours is known as spectrum.
SECTION B ( 2 MARKS)
1) What is the cause of myopia?
Ans a) Elongation of eyeball
b)Eyelens become thick.
2) List four common defects of vision of human eye.
Ans Myopia(short-sightedness), Hypermetropia(long –sightedness), Presbyopia, Astigmatism
3)Draw a labeled diagram of human eye
Ans NCERT textbook Page No. 187 , Fig. 11.1
4) List two causes of hypermetropia.
Ans a) Eyeball becomes too short
b) Focal length of the eyelens is too large
5) a) What is the cause of dispersion?
b) Write prism equation.
Ans a) Dispersion is due to the fact that different colours travel through glass with different
speeds.
b) i + e = A + D
6) What is meant by power of accommodation of the eye.
Ans The ability of the lens to adjust its focal length so that person can see objects lying at all
distances between the near point and far point is called power of accommodation.
7) Give two conditions for the formation of rainbow
Ans a) Presence of water droplets.
b) the back of observer is towards the sunlight.
8) The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of
the lens required to correct the problem.
Ans Given, far point, x= 80 cm
f = -x or f= -80 cm = -0.8 m
P = 1/f = 1/ (-0.8)
P = -1.25 D
Nature of lens is concave lens.
9) Why does the sky appear dark instead of blue to an astronaut?
Ans As there is no atmosphere , there is no scattering of light.
10)Why is normal eye not able to see clearly the objects placed closer than 25 cm?
Ans Because ciliary muscles cannot contract the eyelens beyond a limit .
SECTION C (3 MARKS)
1) Why do stars twinkle?
Ans The twinkling of stars is due to atmospheric refraction. The star light on entering into the
earth’s atmosphere undergoes refraction continuously. Due to atmospheric conditions , the path
of rays of light coming from the stars keeps on changing. The apparent position of the stars
fluctuates and amount of star light entering into the eyes flickers.
2) Why do planets do not twinkle?
Ans The planets are much closer to the earth and considered as collection of point sized sources.
The intensity of light entering our eye from all point sized sources comes to zero thereby
cancelling the twinkling effect.
3) a)What is long- sightedness ?
b) Describe the ray diagram how this defect can be corrected by using spectacles?
Ans a) In this defect, a person can see distant objects clearly but not able to see near by objects.
4) What is presbyopia? What is its cause ? How it can be corrected?
Ans A person is not able to see either near by objects or distant objects clearly in this defect.
Cause- The power of accommodation of the eye decreases due to weakening of ciliary muscles and
flexibility of the eye lens.
It can be corrected by using bifocal lenses.
5) Why does the sun appear reddish early in the morning and at the time of sunset?
Ans The sun is near the horizon at the time of sunrise and sunset. At these times, sunlight has to
travel longer distance in the earth’s atmosphere. The blue light of shorter wavelength is scattered
away by the air molecules and light that enters into our eyes is of longer wavelength which gives
reddish appearance to the sun.
6) What do you understand by atmospheric refraction? List the applications of atmospheric
refraction in nature.
Ans The refraction of light caused by earth’s atmosphere having layers of air of various optical
densities is called atmospheric refraction.
Applications- 1) Twinkling of stars
2) Apparent positions of stars.
7) A 14 year student is not able to see clearly the questions written on the blackboard placed at
the distance of 5 m from him.
a) Name the defect of vision he is suffering from.
b) Name the type of lens used to correct this defect.
c) With the help of labeled diagram show how this defect can be corrected.
Ans a) Myopia
b) Concave lens
c) NCERT book , P.No. 189, fig. no. 11.2
8) What is Tyndall effect? Explain two applications of Tyndall effect.
Ans The phenomenon of scattering of light by the colloidal particles is called Tyndall effect.
Applications: 1) Blue colour of sky- In the atmosphere, blue colour ( shorter wavelength) is
scattered the most and is visible to human eye.
3) Red colour of danger signals- The red colous is least scattered by fog or smoke. So it can be
seen in the same colour at a distance.
Chapter 12
Chapter: Electricity
Topics
1) Conductors & Insulators.
2) Electric Current
3) Electric Potential and Potential difference.
4) Electric circuit and its components.
5) Ohm’s Law
6) Resistance.
7) Factors on which resistance of a Conductor depends.
8) Combination of resistors in series and parallel.
9) Heating effect of electric current
10) Electric Energy
11) Electric Power
12) Commercial unit of electric energy.
13) Rating of an electric appliance.
Question /Answer
1) What is an electric current?
2) What is electrostatic potential?
3) What is S.I unit of electric potential?
4) Name the apparatus used to measure electric current in a circuit.
5) Show the symbols for
i)
a battery
ii)
a fixed resistance.
6) If net charge Q flows across any cross section of a conductor in time t, what is the current (I)
flowing through the cross section?
7) How much energy is given to 5 coulomb of charge passing through a 12V battery?
8) State Ohm’s law?
9) Name the Physical quantity which is equal to V/I ?
10) Define Ohm?
11) State the S.I unit of resistivity.
12) Name the metal that has the highest conductivity.
13) Why is tungsten metal selected for making filament of incandescent lamp bulbs?
14) You are provided with three resistors of resistances R1,R2 and R3. Write the formula for the
equivalent resistance R when these resistors are connected in (i) Series
(ii) Parallel
15) Write the commercial unit of measurement of electric energy.
16) Which bulb has greater resistance a 100 watt bulb or a 60 watt bulb?
17) Write the factors on which resistance of a conductor depends.
18) A copper wire of resistivity 1.6 x 10-8 Ohm meter has a cross sectional area of 20 x 10-4cm.
Calculate the length of this wire required to make a 10 Ohm coil.
19) Write the different formulae of Calculate power.
20) Express 1 Kwh in joules.
21) What is the charge possessed by an electron.
22) An electric motor takes 5A from a 220V . determine the power of the motor and the energy
command in 2h.
Answers
1) The rate of flow of electric charges is called electric current.
2) The work done in bringing a unit charge from infinity to appoint is called electrostatic
potential.
3) Volt.
4) Ammeter.
5) (i)
5(ii)
6) I = Q/t
7) Charge Q = 5 coulomb Voltage V=12V
E = Q x V = 5 x 12 = 605
8) “At constant temperature, the current flowing through a conductor is directly proportional to
the potential difference across its ends or V ά I”
9) At constant temperature V/I is called the resistance of a given wire.
10) If potential difference the ends of a conductor is Volt and the current flows though the
conductor is 1 ampere, the resistance of the conductor is 1 Ohm.
11) S.I unit of resistivity – Ohm meter (Ώm)
12) Silver.
13) Due to high value of resistivity and high melting point of tungsten. Tungsten is incandescent
lamp bulbs.
14) In series Rs = R1 + R2 + R3
In parallel 1/Rp = 1/R1 + 1/R2 + 1/R3
15) Kilo watt hour (KWh)
16) The resistance of 60 watt bulb is greater.
17) The resistance of a conductor depend on (i) Length (ii) area of cross–section.
(iii) nature of
material of the conductor.
18) Resistivity (P) = 1.6 x 10-8 Ohm meter.
Area of cross section (A) = 20 x 10-4 cm2 = 20 x 10-8 m2
Resistance (R) = 10 Ohm
R = RA/P = 10 x 20 x 10-8 /1.6 x10-8 = 2000/16 = 125m
19) Power (P) = V x I = I2 x R = V2/R
20) 1 Kwh = 3.6 x 106 Joules
21) 1.6 x 10-19 coulomb
22) Current (I) = 5A
23) Voltage (V) = 220 V
P = V x I = 220 x 5 = 1100 w
Energy consumed in 2 hours
= 1100 w x 2h
= 2200 wh
= 2.2 Kwh
Multiple choice questions:- (one mark)
1.What is the least count of the following voltmeter ?
(a) 0.5V (b) 0.1V (c) 0.05V (d) 0.005V
2. Four students measured the following readings by observing, the position of pointer of voltmeter
(a) 2.5 V (b) 2.0 V (c) 2.2 V (d) 2.4 A
3.The current through a resistor connected in an electric circuit and the potential difference across its
ends are shown in the diagrams.
4.The symbol of a cell used in electric circuits is
5.The following ammeters and voltmeters are available in the laboratory to find equivalent resistance
of two resistors R1 and R2 in parallel
Ammeters :
A1 of Range 0 to 300mA : Least Count 10mA
A2 of Range 0 to 100mA : Least Count 20mA
Voltmeters :
V1 of Range 0 to 5V : Least Count 0.2 V
V2 of Range 0 to 4V : Least Count 0.4 V
The best combination of voltmeter and ammeter would be
(a) ammeter A1 and voltmeter V1 (b) ammeter A1 and voltmeter V2
(c) ammeter A2 and voltmeter V1 (d) ammeter A2 and voltmeter V2
6. In the experiment on finding equivalent resistance of two resistors, connected in series, four
students I, II, III and IV set up the circuit as shown below :
The correct connections have been made by student (a) I
(b) II (c) III (d)
7.A student draws the circuit diagram as shown. The parts labelled X, Y and Z respectively are :
(a) Ammeter, resistor, voltmeter
(b) Ammeter, voltmeter, resistor
(c) Voltmeter, resistor, ammeter
(d) Voltmeter, ammeter,
8. The following circuit diagram shows the experimental set up for the study of dependence of current
on potential difference. Which two circuit components are connected in series.
(a) battery and voltmeter
(b) ammeter and voltmeter
(c) ammeter and rheostat
(d) resistor and voltmeter
9.To determine the equivalent resistance of two resistors in parallel combination a circuit is shown
below. The component of the circuit whose terminals are wrongly connected is :
(a) rheostat (b) cell (c) volt meter (d) ammeter
10.Two resistances R1 and R2 are to be connected in series combination. Out of the following the
correct combination is shown in :
(a) only A (b) only B (c) only C (d) all of them A, B and C
Ans:1) 0.05v
2) c
3. c
4.b
5.d
6.iii
7.a
8.a
9.d
10.d
One mark questions from electricity
Q1. Define charge. Give its S.I unit
Q2. The length of a wire is doubled. How is its resistivity affected ?
Q3.What are S.I units for resistance and resistivity?
Q4. Name the instrument used to measure the electric potential difference?
Q5What is relation between 1 J and1 Volt
Q6Name the unit used in selling electrical energy to consumers
Q7 State the relation between the power p consumed by a device its resistance R
and current I flowing through it?
Q8 What happens to resistance of a conductor when temp increases?
Q9 n resistors each of resistance R are connected in series in an electric circuit
what is the total effective resistance of the circuit/
Q10.Is electric current is a scalar or vector quantity?
Answers for one mark questions
ANS1 . A basic entity capable of independent existence .It is of two types. positive
and negative charges
ANS 2.resistivity of a given material is constant .therefore it is not affected by
change in length of wire
ANS3. S.I Unit of resistance is Ωand Ωm
ANS4 .Voltmetre
ANS5. 1Joule =Ivolt X 1 Coulomb
ANS6 Kilowatt hour(kwh)
Chapter 13
MAGNETIC EFFECT OF CURRENT
MAGNETIC FIELD AND FIELD LINES
A compass needle is, in fact, a small barmagnet. The ends of the compass needle point approximately
towardsnorth and south directions.
The end pointingTowards north is called northseeking or north pole.
The other end that points towards south is calledsouth seeking or south pole.
like poles repel, while unlike poles of magnets attract each other.
The regionsurrounding a magnet, in which the force of the magnet can bedetected,is said to have a
magnetic field.
The iron filings arrange themselves in a pattern as shown Fig.The lines along which the iron filingsalign
themselves represent magnetic field lines.
Magnetic field is a quantity that has both direction and magnitude.
The direction of the magnetic field is taken to be the direction in which anorth pole of the compass
needle moves inside it. Therefore it is takenby convention that the field lines emerge from north pole
and merge atthe south pole (note the arrows marked on the field lines) Inside the magnet, the
direction of field lines is from its south pole to itsnorth pole. Thus the magnetic field lines are closed
curves.
The relative strength of the magnetic field is shown by the degree ofcloseness of the field lines.
The field is stronger, that is, the force actingon the pole of another magnet placed is greater where
the field lines arecrowded.
No two field-lines are found to cross each other. If they did, it wouldmean that at the point of
intersection.
MAGNETIC FIELD DUE TO A CURRENT-CARRYING CONDUCTOR
an electric current through ametallic conductor produces a magnetic field around it.
Right Hand Thumb – Rule:-
Imagine that you are holding a current-carrying straightconductor in your right hand such that the
thumb points towardsthe direction of current. Then your fingers will wrap around theconductor in the
direction of the field lines of the magnetic field,
Magnetic Field due to a Current in a Solenoid:-
A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is
calleda solenoid.
The patternof the magnetic field lines around a current-carrying solenoid isshown in Fig.
one end of the solenoidbehaves as a magnetic north pole, while the other behaves as thesouth pole.
The field lines inside the solenoid are in the form ofparallel straight lines.
the magnetic field isthe same at all points inside the solenoid. That is, the field is
uniform inside the solenoid.
A strong magnetic field produced inside a solenoid can beused to magnetise a piece of magnetic
material, like soft iron,when placed inside the coil. The magnet so formed iscalled an electromagnet.
Fleming’s left-hand rule:-
According to this rule, stretch the thumb,forefinger and middle finger of your left handsuch that they
are mutually perpendicular(Fig. 13.13). If the first finger Points in thedirection of magnetic field and
the secondfinger in the direction of current, then thethumb will point in the direction of motion orthe
force acting on the conductor.
Devices that use current-carrying conductors and magnetic fields are electric motor, electric
generator, loudspeakers, microphonesand measuring instruments.
An electric motor is a rotating device that converts electrical energy tomechanical energy.
Electric motor is used as an important componentin electric fans, refrigerators, mixers, washing
machines, computers, MP3players etc.
ELECTROMAGNETIC INDUCTION:This was first studied by English physicist Michael Faraday. In 1831, Faraday made an important
breakthrough by discovering how a moving magnet can be used to generate electric current.
The process, by which a changingmagnetic field in a conductor induces a current in another
conductor,is called electromagnetic induction.
Fleming’s right-hand rule
we can use a simple ruleto know the direction of the induced current. Stretch thethumb, forefinger
and middle finger of right hand so thatthey are perpendicular to each other, as shown inFig. 13.18. If
the forefinger indicates the direction of themagnetic field and the thumb shows the direction of
motionof conductor, then the middle finger will show the directionof induced current. This simple rule
is called Fleming’s right-hand rule.
DOMESTIC ELECTRIC CIRCUITSIn our homes, we receive supply of electric power through a main supply (also called mains), either
supported through overhead electric poles orby underground cables. One of the wires in this supply,
usually withred insulation cover, is called live wire (or positive). Another wire, withblack insulation, is
called neutral wire (or negative). In our country, thepotential difference between the two
is 220 V.
Electric fuse is an important component of all domestic circuits.
A fuse in a circuit prevents damage to the appliances and the circuit due to overloading. Overloading
can occurwhen the live wire and the neutral wire come into direct contact.
MAGNETIC EFFECTS OF CURRENT
Q1 Direction of the current produced by a generator is given by:
(a)
(b)
(c)
(d)
Fleming’s right hand rule.
Fleming’s left hand rule.
Ampere’s swimming rule.
Right Handed Thumb rule.
Q2 The magnetic field lines inside a current carrying solenoid are:
(a) parabolic.
(b) curved.
(c) Straight.
(d) Circular.
Q3 At the time of short circuit, the current in the circuit:
(a) reduces substantially.
(b) doesnot change.
(c) increases heavily.
(d) vary continuously.
Q4 A rectangular coil of copper wires is rotated in a magnetic field.The direction of the induced
current changes once in each:
(a)
(b)
(c)
(d)
Two revolutions.
One revolution.
Half revolution.
One fourth revolution.
Q5 The magnetic field inside a long straight solenoid carrying current:
(a)
(b)
(c)
(d)
Is zero.
Decreases as we move towards its ends
Increases as we move towards its ends
Is same at all points
Q6 A medical technique based on magnetic phenomenon is:
(a) NRI
(b) MRI
(c) CRI
(d) FRI
Q7 SI unit of magnetic field is
(a)
(b)
(c)
(d)
Ampere
Tesla
Curie
Joule
Q8 In Fleming’s Right Hand Rule, the index finger denotes the direction of the:
(a)
(b)
(c)
(d)
magnetic field
induced current
motion of the conductor
magnetic flux
Q9 The magnetic field produced due to a circular wire at its centre is:
(a)
(b)
(c)
(d)
in the plane of the wire
perpendicular to the plane of the wire
at 45 degree to the plane of the wire
at 60 degree to the plane of the wire
Q10 Which of the following correctly describes the magnetic field near a long straight wire?
(a)
(b)
(c)
(d)
The field consists of straight lines perpendicular to the wore
The field consists of straight lines parallel to the wire
The field consists of radial lines originating from the wire
The field consists of concentric circles centered on the wire
Answers :
Q1 (a)
Q2(c)
Q3(c)
Q4(c)
Q5(b)
Q6(b)
Q7(b)
Q8(a)
Q9(b)
Q10(d)
MAGNETIC EFFECTS OF CURRENT
2Marks questions
1. Two circular coils A and B are placed close to each other. If the current in the coil A
is changed, will some current be induced in the coil B? Give reason.
2. What is magnetic field line. List any three properties of magnetic field lines?
3. What is Fleming’s left hand rule?
4. What do you mean by Solenoid?
5. Explain the function of earth wire. Why is it necessary to earth metallic appliances?
6. Explain the term short circuiting?
7. An electric oven 2 KW power rating is operated in a domestic circuit (220 V) that
has a current rating of 5 A. What result do you expect on putting on the Oven?
8. What is an electromagnet? Write the factors on which strength of electromagnet
depend?
9. What is Overloading?
10. A 1m solenoid has 200 turns of wire, while 1/2 m solenoid has 50 turns of wire.
Which solenoid has more number of turns per unit cm?
ANSWERS
Ans1. By changing current in the coil A , a current will be induced in the coil B which is placed
close to A. This is due to the reason that magnetic field lines linked with A also gets linked with B
due to its being close to A. When the current in A changes, magnetic field lines linked with A
change. Obviously, magnetic field lines linked with B also change. As a result of this, current is
induced in the coil B. This phenomenon is called as mutual induction.
Ans.2 Magnetic field line is a path along which a free north pole tends to move. The direction of
magnetic field at a point is determined by placing a small compass needle.
Properties:
a) The relative strength of magnetic field lines is given by the degree of closeness of the field
lines.
b) No two magnetic field lines can ever intersect each other at any point in space.
c) Magnetic field lines always directed from North Pole to the south pole of a magnet.
Ans3. Fleming’s left hand rule states that if we stretch the fore finger, the centre finger and the
thumb of our left hand mutually perpendicular to each other then the fore finger shows the
direction of magnetic field and the central finger indicate the direction of current, then the thumb
will point towards the direction of motion of conductor.
Ans4. A solenoid is a coil having large number of circular turns of wire wrapped in the shape of a
cylinder. On passing electric current, a magnetic field is developed. Magnetic field lines are drawn
inside. The field is along the axis of solenoid such that one end of the solenoid behaves as the
north pole and other as south pole. Therefore, the field of solenoid is similar to that of a bar
magnet.
Ans5. Earth wire is used as a safety measure especially for those appliances that have a metallic
body. E.g: Electric Heater, Electric Toaster etc. The metallic body is connected to the earth wire,
which provides a low resistance conducting path for the current. Thus it ensures that any leakage
of current to the metallic body of the appliances keeps its potential to that of the earth and the
user may not get a severe shock.
Ans 6. Short circuiting takes place in domestic power supply if the live wire and the neutral wire
come into direct contact either due to some fault in an electric appliance or due to damage to
insulation of live wire.
Ans7. Power (P) = 2 KW = 2000 W
V = 220 V
𝑃
2000
Current drawn by the appliance I = 𝑉 = 220 = 9.09 A
The fuse rating is 5 A hence it will melt and break the circuit.
Ans8. An electromagnet is a type of magnet in which magnetic field is produced by the flow of
electric current. Very strong electromagnets can be produced by binding an insulated copper wire
on a soft iron core. When a current is passed through a solenoid, a magnetic field is produced.
Now if a soft iron core is placed inside a solenoid, the strength of the magnetic field becomes very
large. The reason for a large increase in magnetic field is due to the fact that iron gets magnetized
by induction.
Factors affecting strength of electromagnet:
1. Number of turns: Strength of electromagnets is directly proportional to the number of
turns.
2. Current flowing: Larger the current flowing through the wire, stronger is the
electromagnet.
3. Length of Air Gap: Lesser the length of air gap between poles, stronger is the
electromagnet.
Ans9. The supply wire as well as wires used in household wiring has the specific rating. The
rating of 15 A means that if a current upto 15 A is passed through a circuit, there is no likely
damaged feared to the circuit. But if a current more than maximum allowed limit is passed,
there may be excessive heating of the wire and it may damage the wiring. This is called
overloading.
Ans10 For first solenoid,
No. of turns=200
Length =1m=100cm
Therefore, the no. of turns per unit cm=200/100=2
For second solenoid
No. of turns=50
Length=1/2m=50cm
Therefore, no. of turns per unit cm=50/50=1
Thus, 1m solenoid has more no. of turns per unit cm.
3 Marks Questions
Q1 Define magnetic field. A compass get deflected when brought near a bar magnet. Why? List the
properties of magnetic field lines.
Ans 1 The region around a magnet where magnetic force can be experienced is called magnetic field .
A compass needle gets deflected due to the force acting on its poles due to the bar magnet.
Properties of Magnetic field:
1 The directions of magnetic field lines is from north pole to the south pole.
2 They are closed curves.
3 Two magnetic field lines can never be intersect.
Q2 A coil of insulated copper wire is connected to a galvanometer. What happens if a bar magnet is:
1 pushed into the coil?
2 Withdrawn from inside the coil?
3 held stationary inside the coil?
Ans2 (1) When a bar magnet is pushed into the coil, due to electromagnetic induction, an induced
current is produced. The galvanometer show deflection.
(2) Same as above but deflection will be in the opposite direction.
(3) No deflection.
Q3 Name and state the rule to determine the direction of a
(1) Force experienced by a current carrying straight conductor placed in a magnetic field which is
perpendicular to it
(2) Magnetic field produced around a current carrying circular loop
(3) Current induced in a coil due to its rotation in magnetic field.
Ans 3(1) Fleming’s Left hand rule.
(2) Maxwell’s right hand Thumb Rule.
(3) Fleming’s Right hand Rule.
Q4 What are the essential precautions to be followed while using electricity?
Ans4 Precautions to be followed for using electricity are:
1 Switch off all the switches including main switch whenever there is sparking or fire.
2 Fuses should be always connected to the live wire. The earth wuire must be connected to the
body of electric appliances.
3 Fuse must be of proper rating and should always be connected to live wire.
4 Always put dry rubber shoes while repairing the circuit.
Q5 How does a solenoid behave like a magnet? Can you determine the north and south pole of a
current carrying solenoid with the help of a bar magnet? Explain.
Ans A current carrying solenoid behave like a bar magnet and the polarity of its ends depends
upon the direction of current flowing through it. In order to determine the polarities of its ends,
place it in a brass hook and suspended it with a long thread so that it moves freely. Bring north
pole of a bar magnet near one of its ends. In case the solenoid moves towards the bar magnet, the
end of the solenoid is a south pole and in case the solenoid moves away from the magnet, the end
of the solenoid is its north pole. The polarity of the other end of the solenoid can similarly be
determined.
5 Marks Questions
Q1
a) Mention the factors on which the direction of forces experienced by a current carrying
conductor placed in a magnetic field depend.
b) Under what condition is the force experienced by a current carrying conductor placed in a
magnetic field depend.
c) A proton beam is moving along the direction of a magnetic field. What force is acting on
proton beam.
Q2 Briefly explain an activity to plot the magnetic field lines around a straight current carrying
conductor. Sketch the field pattern for the same, specifying current and field directions.What happens
to this field,
(i) If the strength of the current is decreased?
(ii) If the direction of the current is reversed?
Q3 Briefly explain an activity to plot the magnetic field lines around a bar magnet. Sketch the field
pattern for the same specifying field directions.
A region 'A' has magnetic field lines relatively closer than another region 'B'. Which region has
stronger field? Give reason to support your answer.
Answers
Ans1 (a) The direction of force experienced by a current carrying conductor placed in a magnetic field
depends upon the direction of current and direction of magnetic field.
b) The force experienced by current carrying conductor placed in a magnetic field is maximum when
the direction of current is at right angles to the direction of the magnetic field.
c) Magnetic force.
Ans2Brief explanation of activity:
Connect the circuit as shown in the figure below. Switch on the battery so that the current begins to
flow. Sprinkle some fine iron filings around the current carrying wire. Tap the surface gently. The iron
filings get arranged in concentric circles.
When current is decreased, field gets decrease
When the current is reversed, field also gets reversed
Ans3 A magnet is placed on a sheet of paper. A compass needle is placed near the North Pole. The
position of its two ends is marked with the help of a sharp pencil. Now the compass is moved in such a
way that its south end occupies position occupied by north end previously. Again the two ends are
marked with sharp pencil. In this way, process goes on step by step till the south pole of the magnet is
reached. Now all points are joined to get a smooth curve which represents a field line. In this way
many field lines can be drawn Region A has stronger magnetic field
Because the strength of the field is proportional to the relative closeness of field lines.
SOURCES OF ENERGY
KEY CONCEPTS & GIST OF THE LESSON
Characteristics of a good fuel:
1) High calorific value
2 Less smoke
3) Less residue after burning
4) Easy availability
5) Inexpensive
6) Easy to store and transport
Fossil fuels: were formed millions of years ago, when plants and animal remains got buried
under the earth and were subjected to high temperature and pressure conditions. E.g.: Coal,
Petroleum, etc.
These fossil fuels are non renewable sources of energy and cause environmental problems due
to pollution.
Thermal power plants:
(i) Use coal, petroleum and natural gas to produce thermal electricity.
(ii) Electricity transmission is very efficient.
(iii) The steam produced by burning the fossil fuels runs the turbine to produce electricity
Hydro power plant:
(i) It is the most conventional renewable energy source obtained from water falling from a
great height.
(ii) It is clean & non polluting source of energy.
(iii) Dams are constructed to collect water flowing in high altitude rivers. The stored water
has a lot of potential energy.
(iv) When water is allowed to fall from a height, potential energy changes to kinetic energy,
which rotates the turbines to produce electricity.
Disadvantages of Hydro power plant:
(i) Highly expensive to construct.
(ii) Dams cannot be constructed on all river sites.
(iii) Large areas o human habitation and agricultural fields get submerged.
(iv) People face social and environmental problems.
Non conventional sources:
(1) Bio mass:
o It is the source of the conventionally used fuels that are used in our
country. E.g.: Cow dung cakes, fire-wood, coal, charcoal
o Bio gas: It is a mixture of gases produced during decomposition of bio
mass in the absence of Oxygen. (Anaerobic Respiration). Methane is the
major component of bio gas.
o Bio gas plants: Animal dung, sewage, crop residues, vegetable wastes,
poultry droppings, etc. are used to produce Bio gas in Bio gas plants.
(2) Wind energy:
o It can be converted into mechanical and electrical energy.
73
o Kinetic energy of the wind is used in running of wind mills, which are used
to lift water, grind grains, etc.
o Wind millo Advantages: (i) Eco friendly (ii) Renewable
o Disadvantages: (i) Wind speed not uniform always.
(ii) Needs a large area to erect series of wind mills.
(iii) Big amount of investment is needed.
(iv) Out put is less as compared to investment
(3) Solar energy:
o Solar radiations can be converted electricity through solar cells
(photovoltaic cells).
o Photovoltaic cells convert solar radiations directly into electricity through
silicon solar cells.
o Solar cells arrange on a large flat sheets form a solar panel.
o Solar cookers are painted black from outside and a large glass plate to trap
solar radiations by green house effect.
o Advantages of Solar cookers:
(i) Eco friendly
(ii) Renewable
(iii) Used in rural areas.
(iv) Retains all the nutrients in food due to slow cooking.
o Disadvantages of solar cooker:
(i) Silicon cells are expensive.
(ii) Solar radiations are not uniform over earth‘s surface.
(iii) Cannot be used at night or on cloudy days.
(iv) Cannot be used to make chapattis for frying as these
require a temperature of 1400C or more.
(Maximum temperature of 1000C only can be
achieved in a solar cooker)
o Other solar devices- Solar water heater, Solar furnace
(4) Geo thermal energy:
(i) Energy harnessed from the heat of the sun is called Geo thermal energy.
(ii) Magma is formed when this heat melts the rocks. The molten rocks and hot
gases are called magma
(iii) The magma gets collected at some depths below the earth‘s surfaces. These
places are called ‗Hot spots‖
(iv) When underground water comes in contact these hot spots, it changes into
steam, which can be used to generate electricity.
o Advantages of Geo thermal energy:
(i) Renewable
(ii) Inexpensive
o Disadvantages of Geo thermal energy:
(i) Only few sites available for harnessing energy.
(ii) Expensive
(5) Nuclear energy:
(i) Energy released when some changes take place in the nucleus of the atom of a
substance, is called Nuclear energy.
(ii) It is used for heat generation, fuel for marine vessels.
74
o Advantages of Nuclear energy:
(i) Alternative source of energy due to depletion of fossil fuels.
(ii) From a small amount of fuel, a large amount of energy is released.
o Disadvantages of Nuclear energy:
(i) Risk of nuclear waste leakage
(ii) High cost of setting up of nuclear plant
(iii) Pollution of environment.
(6) Energy from the sea(A) Tidal energy: Locations in India – Gulf of Kutch, Gujrat & W. Bengal
(i) Depends upon harnessing the rise and fall of sea level due to tidal action.
(ii) Dams are constructed across a narrow part of sea and turbine converts tidal
energy into electrical energy.
Disadvantages: Uniform tidal action is not seen
(B) Wave energy:
(i) Kinetic energy of the waves of sea are used to rotate turbines..
(ii) These turbines generate electrical energy
Chapter 14
Sources of energy
ENERGY:-“ Energy is the capacity to do work is called energy”
Sources Of Energy:1. Solar Energy
2. Heat Energy
3. Electrical Energy
4. Wind Energy, etc.
CONDITIONS FOR GOOD SOURCE OF ENERGY:High Calorific Value
Easy Availability
Eco friendly
Easy to store and transport
Less expensive
CLASSIFICATION OF SOURCES OF ENERGY
It is broadly classified into
Conventional energy: are used extensively and meet major portion of our energy requirement, e.g coal
and petroleum.
non-conventional energy: are not used extensively and meet our energy requirement only on a limited
scale . e.g. Solar, wind, tidal and geothermal etc.
3.Renewable energy sources are inexhaustible and are renewed by nature itself. Solar, wind, tidal,
hydro and biomass are few examples.
4.Non-renewable energy sources are exhaustible within a definite period of time depending upon its
usage. Fossil fuels (coal, oil, gas) and nuclear fuels are few examples.
FOSSIL FUELS:These are obtained from the dead remains of plants and animals. Eg coal and petroleum and natural
gas.
Disadvantages:air pollution.
Acid rain
Thermal power plant:These power plants use coal , petroleum to produce electricity.
Advantages:Electricity transmission is more efficient.
Disadvantage:Causes pollution.
Hydro power plant:In hydro power plants energy of the flowing water is used in the production of electricity.
Advantage:Eco friendly
Disadvantage:Dams can be constructed at a limited site.
BIO MASS:- it is defined as a living matter or its residue.
BIO ENERGY:- energy obtained from bio mass.
BIO GAS:_ it is obtained ab anaerobic decomposition of bio mass in bio gas plant.
Bio gas is a mixture of CH4, CO2, H2S, H2,N2.
SOLAR ENERGY:It is the main source of energy in this universe, solar energy is directly converted into heat energy by
the use of solar cooker.
It is directly converted into electrical energy with the help of solar cells.
ADVANTAGES
Renewable source of energy
Pollution free
DISADVANTAGES
Capital cost is very high
Solar radiations are not uniform
WIND ENERGY
kinetic energy of wind is converted into mechanical energy and electrical energy with the help
of wind mill.
ADVANTAGES
Wind is Renewable and free of cost
Pollution free
DISADVANTAGES
Capital cost is very high
Large area of land is required
GEOTHERMAL ENERGY
Internal heat of the earth is used to generate electricity
ADVANTAGES
Geothermal energy is cheaper
Used as space heating for buildings
DISADVANTAGES
Low overall power production efficiency (about 15%)
Large areas are needed foe exploitation of geothermal energy
Energy from sea:This energy is available in three forms:Ocean thermal energy:- it is a solar energy stored in the ocean in the form of heat.
Tidal energy:- energy derived from rising and falling ocean tides is called tidal energy.
Wave energy :- energy possessed by oceans and sea waves is called wave energy
NUCLEAR ENERGY:Energy obtained from the nucleus of an atom is called nuclear energy.
Radioactive elements generate large amount of nuclear energy.
TYPES OF NUCLESR ENERGY:Nuclear fission
Nuclear fusion
Advantages:It is an alternative source of energy.
From small amount of fuel large amount of energy is produced.
Disadvantages:High cost of setting up of nuclear plant.
Risk of nuclear waste leakage.
One mark questions
Q.1 Name two green house gases.
Q.2 what type of energy is possessed by wind?
Ans. Kinetic energy.
Q.3 Name any two materials used for fabricating solar cells.
Ans. Silicon and Germanium.
Q.4 Name the main constituents of biogas.
Ans. Methane.
Q.5 What type of reactions occur inside the sun which produces solar energy?
Ans. Nuclear fusion.
Q.6 What type of radiations are emitted by hot electric iron ?
Ans. Infrared radiations.
Q.7 What is the minimum wind velocity required for obtaining useful energy with a wind mill?
Ans. 15 Km/hr.
Q.8 State the energy conversion taking place in hydro power plant?
Ans.P.E. of the water stored in the reservoir is converted into electricity.
Q.9 Give two examples of fossil fuel .
Ans. Coal ,petrol.
Q.10 Why does acid rain happen?
Ans. Burning of fossil fuel releases oxides of nitrogen,sulphurwhich combine with rain water to
form respective acids.
Short Answer Type Questions{2 marks each }
Q.1 List four activities from our daily life in which solar energy is used.
Ans.(a) Drying of grains (b) Drying of clothes (c) obtaining salt from sea water(d) sun bath taken by
babies.
Q.2 L.P.G. is a better fuel than coal. How?
Ans. L.P.G. is a better fuel than coal because
(a)
(b)
(c)
(d)
It gives smokeless flame.
It does not leave residue behind.
It is easy to store.
It has high calorific value.
Q.3 What do you mean by biomass? Give examples of biomass.
Ans. Animal waste and dead remains of plants constitute biomass.
Eg. Dead plants , animals and cattle dung .
Q.4 State the type of energy conversion taking place in (a) thermal power plant(b) in solar cell.
Ans.(a) chemical energy of coal into electric energy.
(b) light energy into electric energy.
Q5. Expand OTEC .On what principle is it based?
Ans. OTEC means Ocean Thermal Energy conversion.
It is based on the temperature gradient between upper and lower layers of the ocean.
.
Q.6 Give two advantages of classifying energy sources as renewable and non-renewable.
Ans. (i) The classification helps us to decide which of the available energy sources need to be
conserved to ensure their availability for future generations.
(ii)The classification helps us to look for alternative sources of energy like solar and wind energy. It has
therefore accelerated the pace of development of technologies suitable for harnessing new sources of
energy.
Q. 7 What is geothermal energy? What are its advantages?
Ans.It is the energy obtained from hot spots in earth crust.
Advantages(1)Eco-friendly (2) Economical.
Q.8 Distinguish between renewable and non-renewable sources of energy .
Ans.(i)Renewable resources. The resources which are renewed or replenished by nature after some
time are called renewable resources such as ,ground water, forests, wood, solar , energy ,etc.
(ii)Non renewable resources .the resources which are not renewed or replenished by
nature after a shorter perios, are called non renewable resources .e.g.; fossil fuels (coal
,naturalgas,and petroleum)etc.
Non renewable resources of energy are also called exhaustible sources of energy.
Q.9 What are fossil fuels? Give two disadvantages.
Ans. Fossil fuels are formed from the dead remains of plants and animals burried deep under the
earth millions of years ago.
Disadvantages of burning fossil flues are :(i)
Fossil fuels are non-renewable sources of energy and they are formed in a period of
millions of years.
(2)
Q.10
Extensive use of fossil fuels causes environmental pollution
What is solar cooker? Why it is painted black?
Ans. Solar cooker is a device which converts solar energy into heat energy.
It painted black to absorb more and more of solar energy.
Short answer type questions (3 marks each)
Q.1 List three conditions of a good source of energy.
Ans. (a)It should have high calorific value
(b)It should be easy to store and transport.
(c)It should be eco-friendly.
1.
Q2.What is a solar panel? State its two main advantages.
Ans.When solar cells are arranged side by side ,connecting each other is such a way thatotal potential
difference and the total capacity to provide electric current is much increased, the arrangement is
called ‘solar cell panel’.
Advantages of
solar cell panels:(1)Solar energy is renewable source of energy.
(2) Ecofriendly.
Q.3 What is the role plane mirror and glass sheet in a solar cooker ?
Ans. (1) Mirrors are used as reflector in solar cookers to focus the rays of sun to achieve higher
temperature.
(2) Glass sheet is used in solar cooker to facilitate the phenomenon of green house effect.
Q.4 Give two advantages and disadvantages of solar energy.
Ans.
Advantages
(1) It is a renewable source.
(2) It is pollution free.
Disadvantages
(1)It is not present at night or on cloudy days
(2) High efficiency devices to harness this energy
are not fully developed.
Q.5 Biogas is considered to be a boon to the farmers. Give reasons.
Ans. 1. Farmers can produce clean domestic fuel from the wastes like animal dung, dry leaves, dry plants etc.
2. Spent slurry can be used in the fields as manure to increase the fertility of the soil.
3. Biogas can be used to generate electricity.
Q.6 What is a nuclear waste? What are the hazards of nuclear waste to living thing ? How is it
disposed off?
Ans. The by products obtained in a nuclear reaction are called nuclear wastes.
These are radioactive wastes and emit radiation which may cause skin cancer and genetic
disorders.
They can’t be disposed off like other wstes because they are radioactive in nature .Their
disposal is the biggest threat for the scientists.
Q.7 Write two different ways of harnessing energy from ocean.
Ans. The energy can be harnessed from ocean in following ways
(1) Tidal energy –Due to the gravitational pull mainly of the moon on the spinning earth, the
level of the water in the sea rises and falls, is called high and low tides can be harnessed by
constructing a dam across a narrow opening to the sea.
(2) Ocean Thermal Energy- The water at the surface of the sea or ocean is heated by the sun
while the water in deeper section is relatively cold.This difference in temperature is
exploited to obtain energy in ocean-thermal-energy conversion plants.
Q.8 Hydro energy is an indirect source of solar energy.Justify.
Ans. Solar energy is manifested in many forms on earth, one of witch is is hydro
energy.During water cycle,water flowing in rivers and other water bodies evaporates by
heat of sun,condense back in upper atmosphere and
get replenished back thus energy of flowing water is attributed to the sun.
Q.9 (a) State the principle of working of wind mill.
(b) What is the minimum wind velocity required to obtain useful energy with a wind
mill?
(c) Give one limitation of wind mill.
Ans. (a) Wind mill works on the principle of conversion of wind energy into kinetic energy
of blades of wind mill which can be used to do useful work.
(b) 15km/hr
(c)Wind does not blow at sufficiently high speed all the time.
Q.10 Why are we looking at alternate sources of energy?
Ans. We are looking at alternate source of energy because
(1) The fossil fuel reserves in the Earth are limited which may get exhausted soon,
if continued to be used at the current rate.
(2) The use of alternate energy will reduce the pressure on fossil fuels .
(3) The pollution being caused by the burning of fossil fuels can be avoided by
using alternate source of energy like solar energy and wind energy.
Long Answer Type Questions(5marks each)
Q.1.What is the importance of hydropower plants in India? Describe how electric energy is
generated in such plants.Ans. Conversion of hydro energy into electrical energy. To produce hydro
electric power high rise dam is constructed on the river to obstruct the flow of water and thereby
collect it in a large reservoir. In this way height of water level is increased and water gets potential
energy .The water form reservoir is carried through pipes and falls over the blades of turbine which is
connected to armature of a dynamo .when turbine rotates the armature electricity is produced . in
India about one quarter of energy is met through hydro power dams.
Q.2 Draw a simple and labeled diagram of a fixed dome type bio-gas plant. What is the use of residual
slurry and why?
ANS. Major components of biogas. Methane (up to 75%),and other combustible components
hydrogen and hydrogen sulphide . for labeled diagram of fixed dome type bio-gas plants , see fig
below:-
Uses of residual slurry.It is a good manure as it is rich in nitrogen and phosphorous compounds.
Q.3 Manisha loves to cook a variety of food. She is busy all the time baking ,
frying, heating and refrigerating . Shradha insists upon saving the fuels in
cooking activities and tells Manisha how can she save electricity and burning
fuel by adopting simple habits however, Manisha is reluctant to apply any new
cooking style.
(a)Which method would have been suggested by Shradha?
(b) Throw light on values of Manisha. (Value based question)
(c)Discuss the qualities of shradha which you would appreciate.
Ans. B (a)Shradha would suggest the use of solar cooker, to cook food with lid
on , to cook preferably in a pressure cooker.
(b) Manisha is unaware and unconcered about the importance of
saving fuel.she is stiff on her own ways .
(c) Shradha is concerned about energy saving .she is aware of social
problems on energy crisis .
Q.4 What are the environmental consequences of using fossil fuels ?suggest
two ways to minimise the pollution caused by various sources of energy.
Ans. The environmental consequences of using fossil fuels are
(1) The air pollution caused by burning of coal and petrol.
(2) The oxides of carbon ,sulphur,nitrogen produced by the burning of the
fossil fuels combines with rain water to form acid rainand this acid rain is
damaging flora and fauna.
(3) Carbon dioxide gas released by the burning of the fossil fuels leads to
global warming.
Two ways to minimize the pollution
(2) Afforestation that is planting more and more plants
(3) We should go for alternate source of energy.
CHAPTER -15
OUR ENVIRONMENT
1MARK QUESTIONS
Q1. What is meant by ‘biodiversity hot spot’?
ANS. It is a biogeographic region which is a significant reservoir of biodiversity.
Q2.what can one of the main objective of biodiversity?
ANS. The main aim of conservation is to try and preserve the biodiversity that we have inherited.
Q3.What may happen if there is a loss of biodiversity?
ANS. The loss of biodiversity may lead to a loss of ecological stability.
Q4.Why do we seek to build dams?
ANS. Large dams can ensure the storage of adequate water not just for irrigation but also for
generation electricity.
Q5.Why should resource like forests, wildlife and water be used in a sustainable manner ?
ANS. Thiscan meet our needs perpetually if we were to use them in a sustainable manner.
2 MARKS QUESTION
Q1. What is ‘Chipko Movement’? Why should we conserve forest?
ANS.The movement started in reni village in Garhwal to protectthe trees by hugging them and not
allowing cutting of these trees is called Chipko Movement. We should conserve forest:
(e)
(f)
(g)
(h)
To maintain ecological balance.
To conserve biodiversity.
To meet our material aspirations.
To prevent global warming.
Q2 What is a biodegradable waste? If all the waste we generatw is biodegradable ,what impact may
this have on the enviorment?
Ans.Biodegradable waste can easily be broken down into non- poisonous simplest substances by
physical;chemical and biological processes
If all waste we generate is biodegradable, it will have little impact on the
environment as most of the waste is decomposed by decomposers and nutrients will be released back
into the nutrient pool
Q.3What are fossil fuels?Give two examples?
A.Fossil fuels are the non renewable fuels formed due to burying of plants and animals under
sedimentary layers of earth, snow or oil millions of years ago.e.g. coal and petroleum
Q.4 Give four ways which show your enviorment friendliness?
A.1 Taking abus instead of using personal vehicle.
2. Using flouorescent tubes instead of bulbs.
3. Using stairs instead of lift.
4. Wearing an extra sweater instead of using a heating device on cold days.
5. Using hanky instead of tissue paper.
Q5. List any four measures for conserving forests?
ANS. Four measures to conserve forest are:
(e)
(f)
(g)
(h)
Afforestation : It is the practice of growing more trees for various purpose.
Preventing Mismanagement : Forest and their resource should not be over-exploited and
its equitable distribution should be ensured.
People’s Participation : People should be given a stake in regulating the forests because
they manage the forest more efficiently.
Tourisms : It should be increased at the expense of the ecology and government should
check whether tourism is damaging the forest or not.
(4)
NATURAL RESOURCES (M.L.P)
Q1
Define natural resources and name any two ?
Q2.
What are renewable and non renewable natural resources.
Q3.
What is deforestation ?
Q4.
What is afforestation ?
Q5.
Who initiatedChipko Movement?
Q6.
Write expanded forms of IUCN, CITES, IBWL, MAB ?
Q7.
What is water harvesting ?
advantages ?
Q8.
What is meant by three Rs. How should these be followed ?
Q9.
Name any two energy resources which will be exhausted in the future.
alternatives ?
Q10.
What is the significance of Pink and Green pages in Red Data Book ?
Q11.
Suggest a few measures for controlling CO2 is the atmosphere ?
Give two examples each ?
Give consequences of deforestation ?
What is its slogan ?
mention any two water harvesting structures.
List its four
Suggest
Q12.
Prepare a list of five activities that you perform daily in which natural resources can
be conserved or energy utilization can be minimized ?
ANSWERS
Ans1.
Natural resources are those living or non-living substances available in the
normal environment which are being exploited for supporting life and meeting
human requirements. E.g. Land, Soil, Water, and Forest etc.
Ans2.
i)
Renewable / inexhaustible natural resources :- These resources occur in
abundance , they are not likely to be exhausted by human use. E.g. Air, Water,
Solar Energy etc.
ii)
Non-renewable / Exhaustible natural resources :- These resources are likely
to get finished due to continuous human use. E.g.Fossils Fuels, Minerals.
Ans3.
Deforestation :- The indiscriminate cutting of forest cover due to inhuman
reasons leads to deforestation.
Concequences:7. Global Warming
8. Soil Erosion
9. Droughts
10. Floods
11. Landslides
12. Disturbance in rainfall patterns
Ans4.
Afforestation :- plantation of more and more plants to develop forests in all
available land.
Ans5.
ShriSundarLalBahuguna. The slogan of Chipko Movement is five F5 - food,
fodder, fuel, fibre and fertilizer.
Ans6.
IUCN :-
International Union for Conservation of Nature and Natural Resources.
CITES :- Convention on International Trade in Endangered Specious.
Ans7.
IBWL :-
Indian Board of Wild Life.
MAB :-
Man and Biosphere.
Water harvesting is a practice of colliecting rain water in safe storage places
from where it can be used throughout the year both for drinking and irrigation .
The two harvesting structures are :iii. Khadin System in Rajasthan.
iv. Kulhs in Himachal Pradesh.
Advantages :v. It makes rain water percolate slowly underground and recharge ground water.
vi. Harvested rain water can be used for irrigation .
vii. Harvested water can be used for drinking by cattle.
viii. Harvested water provides moisture for crops nearby.
Ans8.
Three ‘R’ are - Reduce, Recycle, Reuse.
Reduce - Minimise the use of natural resources in order to conserve
them.
Recycle - Collect the used and discarded articles such as papers, plastics, glass,
metals etc and send them for recycling to be reused.
Reuse - To reuse again and again like paper, Plastic etc.
Ans9.
Coal and petroleum have a limited stock and hence these will be exhausted in
future . The alternative are :iv. Use of biogas
v. Hydropower
vi. Cultivation of petro Plants.
Ans10.
Pink page are meant for critically endangered species and green pages enter
those species that are recovered and deleted from pink pages.
Ans11. i.
Planting of trees
v. Increased use of alternative sources of evergy instead of fossil fuels.
vi. Avoid burning of litter and crop residue, instead, convert these into
manure.
vii. Smoke from factories should be treated to remove harmful gases before its
discharge into the atmosphere.
Ans12.
i.
Use of fans and lights only when required .
vi. Use CFL in place of conventional electric bulbs / tubes .
vii. Use solar cookers and solar water heating devices instead of using fossil
fuels.
viii. Close taps after use
ix. Avoid use of hose pipe for watering plants.
SAMPLE PAPER NO 1(SA1)
Class –X
Subject- Science
Time :- 3Hrs
Maximum Marks 90
General Instructions:
1.The question paper comprises of two sections A and B .You are to attempt both the section.
2. All questions are compulsory.
3. Question No. 1 to 3 in section A are one mark question.
4. Question No. 4 to 6 are two marks question, to be answered in about 30 words each.
5. Question No. 7 to 18 are three marks question. To be answered in about 50 words each.
6. Question No.19 to 24 are five marks questions. To be answered in about 70 words each.
7. Question No.25 to 33 in section B are multiple choice based on practical skills. Each question is a one mark
question. You are to choose one most appropriate response out of the four provided to you.
8. Question No. 34 to 36 in section B are practical based and carry 2 marks each.
Section –A
1. Why magnesium ribbon is rubbed with sand paper before burning?
2. Write a balance equation to represent the following reaction:-Aluminum reacts with copper chloride to
give aluminum chloride and copper.
3. Write the S I unit of electric charge.
4. Name the respiratory organs of (a) Fish (b) Cockroach.
5. Surface of some metals loose their brightness when they kept in air for a long time. Why?
6. The atomic no. of sodium is 11, fluorine is 9 and Neon is 10. Why are sodium and fluorine very reactive
while Neon show almost no reactivity?
7. Where is bile juice is produced and stored in digestive system and state its role in the digestion of food
?
8. Define neutralization reactions. Give an example in daily life application.
9. Describe an activity to show that acid produce ions only in aqueous solution.
10. What is biogas ? Why is it considered as an ideal fuel ?
11. Define phototropism. Which hormone is responsible for it . How?
12. Calculate the number of electrons that will constitute a flow of charge 7 C.( charge of one electron is
1.6x10-19C.
13. . A person has lost his control over muscular activities.
a) What can be the possible cause?
b) What would you advice the person to overcome the problem?
c) Which value is inculcated?
14. (a) Balance the following equations (i)
CaO(s) +H2O->Ca(OH)2
(ii)
KClO3(s) -> KCl+ O2
(iii)
KNO3 --- K NO2 + O2
(b) Write the type of reaction in each case?
15. When water is added to a white powder ‘A’ vigorous reaction takes place & a large amount of heat is
released. ‘A’ is also used for white washing.
(a). identify the ‘A’
(b) Give the balanced equation.
(c ) Give the name and formula of the product.
16.A piece of wire having resistance R is cut into four equal parts –
(a) How does the resistance of each part compared with the original resistance.
(b) If four parts are joined together in parallel , how will resistance of combination with the resistance
of original wire ?
17.(a) State Fleming’s Left hand rule?
(b) What is a solenoid?
18 .An electric room heater is rated at 2KW .calculate the cost of using it for 2 Hrs. daily for the month of
September ,if each unit cost is 6 Rupees.
19. (i) ) What are endocrine glands?
(ii) Mention the name of secretory part / gland and function of following hormones.(a) Insulin
(b) Progesterone
( c )Oxytocin
20. Two resistors of 2 ohms and 3 ohms are connected in series. Calculate the equivalent resistance and
current when connected across a battery of 10 volts?
What is overloading in domestic circuits?
21. a) Give two example of renewable & non- renewable energy sources.
(b) Why is there need for harnessing non-conventional sources of energy.
( c ) Write the name of eco-friendly energy sources.
22. ( a) Explain in brief the mechanism of circulation of blood circulation of blood in human body.
(b) Lymph is another type of fluid involved in transportation. Justify the statement by two reason.
23. Account for the following –
(a) melting point of ionic compounds are high
(b) Aluminum is more active then iron yet there is less erosion of aluminium when boith are exposed to air.
( c )Solder is used for welding electricals wires together
(d ) a sulphide ore is converted into its oxide to extract the metal .
(e) turnished copper vessels are cleaned with tamarind juice.
Q24:
Give reasons for the following:
(i) A farmer is adding quicklime to his field. Why he is doing so? What other chemical compounds he can
add to his field?
(ii) It is seen that basic solutions also contain H+ (aq) ions, then why they are called basic?
(iii) What may happen if you touch the leaves of nettle plant?
(iv) Why bleaching powder is used for disinfecting drinking water?
SECTION :-B
25. Bottle A contain acetic acid and bottle B contain sodium carbonate solution. When pH paper is dipped in
each of the solution, the colour seen in A and B respectively will be:
a) blue, orange
b) orange, green
c) orange, blue
d) green ,blue
26. On putting of few drops of a liquid on pH strip the colour of pH strips change to green , the liquid is most
probably
(a) Lemon juice3
(b) Dilute HCl
(c) NaOH solution
(d) Water
27. Colourless gas is liberated when HCl acid is added to a solution of washing soda, the name of gas is
(a) Carbon di oxide
(b) Nitrogen di oxide
(c) Sulphur di oxide
(d) Sulphur tri oxide
28. What is the least count of following voltmeter
(a) 0.5 volt
(b) 0.1 volt
(c) 0.05 volt
(d) 0.005 volt
29. The equivalent resistance of 4 ohm, 5 ohm ,2 ohm, is 6.33 ohm. Then how can they be connected z
(a) X
b) Y
c) Z
(D) None of these
30. In given circuit voltmeter reading will be
(a) 0 volt
(b) 5 volt
(c) 1 volt
(d) 2 volt
31.The oxygen evolved during photosynthesis from
(a) Spliting of carbon di oxide
(b) From air
(c) Splitting of water
(d) None of above
32. Before the testing of leaf for starch at end of experiment light is necessary for photosynthesis , the
experimental leaf should be boiled in
(a) water
(b) alcohol
(c) KOH solution
(d) HCl solution
33. In the experiment demonstrating respiration in germinating seeds, KOH is used to
(a)absorb CO2 produced by the seeds
(b) Absorb O2 present in flask
(c) Absorb H2O vapour released by the seed
(d) Liberate O2 to be used by the seed
34. What are indicators? Where are they used?
35. In which way Voltmeter and ammeter are connected in an electric circuit?
36. Why alcohol is not heated directly on a flame?
MODEL ANSWERS SAMPLE PAPER NO 1(SA1)
Section –A
1. To remove coating of MgO.
(1)
2.2Al +3Cucl2

(1)
3. Coulomb.
(1)
2AlCl3 + 3Cu
4. (1) gills (2) Tracheal/Spiracles
(1+1)
5. This is due to formation of undesirable compound such as oxides, Sulphide,
the surface of metals due interaction with air & moisture.
(2)
6. Na=2,8,1Ne=2,8
Carbonates on
F=2,7
Sodium Na & fluorine F have tendency to lose or gain electrons to complete their
Octet.Where as Ne has its Octet complete and is extra stable
7. (1) Bile juice is produced by the liver and stored in Gall bladder. (1+1)
(2) Help in emulsification of fats.
(1)
8. Reaction between acid & base gives salts & water and release energy that is
Neutralization.
Reaction: HCl + NaOHH2O + NaCl + Energy
Antacid (Mg(OH)2) is used to cure acidity in stomach.
(2)
9. Heat a pinch of NaCl with con.H2SO4 in a test tube. Pass HCl gas on dry blue
Litmus paper no change in colour takes place. Now pass HCl through blue litmus solution it turns red.
This is because in aqueous solution H+ ions produced.
10 The fuel gas produced by the animals & plant waste is called bio gas which contains methane.
It is non polluting & has high calorific value. ( 1+2)
11. The growth movement of plants induced by stimulus of light is called phototropism.
Auxins hormone is responsible for it.High amount of Auxins is present in shady or dark half region of
shoot apex which causes high growth & turns the plant towards light source.
12. 1electron=1.6x10-19C
1C=1/ 1.6x10-19
7C=7x1.6x10-19
=11.2x10-19
13. (a) Cerbellum
b) Advice – Not to take alcohol in life
c) Value- concern for human control is lost due to taking of excess of alcohol
(1+1+1)
14. (a) correct balancing of each equation. (1/2 + ½ + ½)
(b) Combination reaction, decomposition reaction, decomposition reaction,(1/2 +1/2+ ½)
15. A is calcium oxide CaO
CaO +H2O---Ca (OH)2
16. (a) Resistance of a wire is proportional to its length. Therefore cut into four
pieces, resistance of each pieces will be R/4.
(b) When 4 pieces each of resistance R/4 are connected parallel, the combined
Resistance will be R’
1/R’=1/R/4+1/R/4+1/R/4+ 1/R/4
1/R’=4/R+4/R+4/R+4/R
1/R’=16/R
R’=R/16
17. See pg no 231 ncert text book (2)
(b) A long coil wounded with insulated copper wire.(1)
18. P=2KW=2000W t=60Hrs September=30days
Energy Units consumed= PxT/1000
=2000x60/1000=120KWH/Unit
Total Cost=120x6=720Rs.
19 (i) correct definition (2)
(1) Insulin –beta cells of pancreas, control sugar level
(2) Progesterone – corpus letum of ovary, maintains pregnancy & fixes the embryo
To uterus wall.
(3)Oxytocin –Pitiutary gland, milk secretion, birth hormone
20. . R = r1 +r2 = 2+3 =5 ohms
I = V/R ,
10/5 = 2 ampere
(1)
( ½ + 1 + ½)
Correct explanation (2)
21.a) Renewable –wind , solar energy
Non Renewable –coal, petroleum, natural gas
b) Sources of fossils are limited & will exhausted with in few decade and
rapid growth of population is increasing demand of more energy.
c) Solar energy
22.
A)
b)1. It drains tissue fluid from the extra cellular space back into blood.
2. it takes lymphocytes and antibodies from the lymph nodes to the blood.
3. Some of the fluid from digestive tract is absorbed in the lymph and store the fluid
Temporarily.
23. (a) Due to presence of strong electrostatic force of attraction between ions
B) This is due to the formation of thin protective oxide layer on the surface of
Aluminum but in case of iron the oxide layer peels off exposing fresh surface to
Corrosion.
C) Because it has low melting point
D) This because oxide can be reduced easily.
E) Because the carbonate layer dissolves in tamarind juice.
24. i) To remove the acidic nature of soil. He can also use calcium hydroxide or chalk.
ii) The conc. Of H ions in basic solution is very less & hence can be neutralized.
iii) Leaves of nettle plant contain stringing hair which secretemethanoci aid. It causes irritation when
touched accidently. A traditional remedy is use of any base.
iv) Bleaching powder liberate free chlorine which kills the germs.
(1+1+2+1)
SECTION –B
25. C
26. A (Lemon juice)
27. A (CO2)
28. B (0.1V)
29. A (X)
30. B (5V)
31. C (splitting of water)
32. B (alcohol)
33. A (absorb CO2by seed)
34. correct explanation
35. voltmeter in parallel Ammeter in series
36. Because it is highly flammable as it has low ignition temperature. Catches fire easily.
SAMPLE PAPER NO 2(SA1)
Science
Class : X
Time : 3 Hrs.
Max. Marks: 90
General Instructions:
1.The question paper comprises of two sections A and B .You are to attempt both the section.
2. All questions are compulsory.
3. Question No. 1 to 3 in section A are one mark question.
4. Question No. 4 to 6 are two marks question, to be answered in about 30 words each.
5. Question No. 7 to 18 are three marks question. To be answered in about 50 words each.
6. Question No.19 to 24 are five marks questions. To be answered in about 70 words each.
7. Question No.25 to 33 in section B are multiple choice based on practical skills. Each question is a one mark
question. You are to choose one most appropriate response out of the four provided to you.
8. Question No. 34 to 36 in section B are practical based and carry 2 marks each.
Section A
Q1. Write the balanced chemical equation for the following reaction:
Sodium + Water Sodium Hydroxide + Hydrogen
Q2. Name the pigment present in plants which can absorb solar energy.
Q3. Write any two characteristics of good fuel.
Q4. What is the difference between sensory and motor neurons? Which part of the brain
maintains posture and equilibrium of the body?
Q5.Identify in the following reaction
(i)
(ii)
The substance oxidized
The substance reduced
Zno + C Zn + CO
Q6. Write the name and chemical formulae of the products formed by heating gypsum at 373
K.
Q7. What is meant by the term magnetic field lines? List any two properties of magnetic field
lines?
Q8. (a) Why cannot a chemical change be normally reversed?
(b) Why is it always essential to balance a chemical equation?
( c) Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Q9. Crystals of copper sulphate are heated in a test tube for some time.
(a) What is the colour of crystals (i) Before heating
(ii) After Heating
(b) What is the source of liquid droplets seen on the inner wall of the test tube during the
heating process?
Q10. (a) What are alloys?
(b) Name the alloy of aluminium used in making aircraft?
( c) Write the names of metals present in solder?
Q11. (a) Classify the following reactions into different types
(i)
(ii)
(iii)
AgNo3 (aq) +Nacl(aq)AgCl(s)+ NaNo3
Cao(s)+H2O Ca(OH)2
2KClO3(s)--------> 2KCl + 3O2
(b)Which of the above reaction(s) is /are participation reaction(s) ?Why is a reaction called
precipitation reaction?
Q12. Define the following terms:(1). Minerals
(2) Ores
(3) Gangue
Q13. What are the different ways in which glucose is oxidized to provide energy in various
organisms?
Q14. You are going through the science notebook of your brother you suddenly come
across a question stating “ What is the reason behind regular formation of cramps in
cricketers? “ Your brother stated that the answer as cramps are developed due to tear
in ligament. Is this answer correct state reason for your answer.
Q15. Which animal or plant hormone is associated with the following
1.
2.
3.
4.
5.
Change at puberty in boys
Goitre
Inhibits growth of plants
promotes cell division
Increased sugar level in blood
6. Dwarfism
Q16. State three advantages of using solar cell to produce electricity. Why is their use for
domestic purposes limited?
Q17 (a) What is meant by saying that the potential difference between two points is 1V?
Name a device used to measure potential difference across a conductor.
(b) Electrical Resistivity of two substances at 200 C are given below
Silver
1.60 × 10-8 Ωm
Copper
1.62 × 10-8 Ωm
Among silver and copper, which one is better conductor ?Why ?
Q18.State Ohm’s Law? How this law can be verified experimentally?
Q19 (a) State two factors on which the strength of magnetic field due to current carrying
conductor depends.
(b) State & explain which rule is used to find the direction of magnetic field due to a straight
current carrying conductor?
Q20. Give reasons for the following
(1) Zinc can displace copper from copper sulphate solution
(2) Silver articles become black after sometime when exposed to air
(3) H2 gas is not evolved when most metals react with HNO3
(4) We apply paint on iron grills
(5) We use gold in jewellery
Q21.(a) Draw a diagram of nerve cell and label on it following
(1) Nucleus
(2) Dendrites
(b) With the help of schematic diagram trace the events occurring when you step on a
sharp object
Q22. (a) Write a short note on
(1) Fuse
(2) Earthing
(b) What is short circuit? what happens if a domestic circuit is short circuited
Q23. Draw human excretory system and label
(1) Left Kidney
(2) Ureter
(3) Urinary bladder
(4) Urethra
Where do reabsorption of water and glucose take place in kidney?
Q24. (a)
What are amphoteric oxides? Give two examples.
(b)
Metals such as Sodium and Potassium are kept immersed is Kerosene, why?
(c)
Give the balanced chemical equation for the reaction between Al and steam.
(d)
Name a non metal
i) Which is a liquid at room temperature?
(ii) Which is lustrous?
Section B
Multiple Choice questions
Q25. A solution has pH7. The solution will be
(a) Neutral
(b) Acidic
(c) Basic
(d) Ionic
Q26.Which gas is evolved in the reaction of Zinc metal and NaOH
(a) Cl2
(b) N2
(c)O2
(d) H2
Q27. Name the scientist who proposed acid- Base theory
(a)Arrhenius
(c) Dalton
(b) Newton
(d) Einstein
Q28. Mathematically form of ohm’s law is:
(a) R=I/V
(b) R= V/I
(c) V= I/R
(d) None of above
Q29. Why do we use thick connecting wire
(a) Thick connecting wires offer negligible resistance
(b) Thick connecting wires offer less resistance
(c) Thick connecting wires offer more resistance
(d) None of above
Q30.The commercial unit of electric power is :
(a) Volt
(b) Ampere
(c) Watt
(d)kWh
Q31. The movement of solvent particles from a region of higher concentration to a
region of lower concentration is known as
(a) Transpiration
(b) Osmosis
(c) Diffusion
(d) None of the above
Q32. The chemical used for carrying out the starch test on a leaf is
(a) Iodine crystal
(b) Iodine powder
(c) Iodine Solution
(d) Potassium Iodide
Q33. The seeds used in experiment to show that co2 is given out during respiration are:(a) Dry seeds
(b) Boiled Seeds
(c) Crushed seeds
(d) Germinated seeds
Q34. Why pickles are not stored in metal containers like Copper, Aluminium?
Q35. Why is KOH kept with germinating seeds ?
Q36. Why are coils of electric toasters and electric irons made of an alloy rather than a
pure metal?
MODEL ANSWERS SAMPLE PAPER NO 2(SA1)
SECTION-A
1. 2Na+ 2H2O-> 2 NaOH +H2
2. Chlorophyll
1
1
3. (i)high calorific value
(ii) Economic
½ +1/2
4. Sensory nerves carry message from muscles to brain , motor nerves to carry message
from brain to the muscles .
1
5. Oxidation C
Reduction ZnO
(1+1)
6. Plaster of paris, CaSO4.1/2 H2O
7. The field lines which emerges from north and merges at south
1+1/2+1/2
(i) They never intersect each other
(ii) They have maximum strength at poles.
8. (a) It cannot be reversed because new substances with new properties are formed.
(b) It is essential to balance the chemical equation to obey law of conservation of mass.
(c) Iron being more reactive than copper displace. So it displace copper from copper
sulphate. Blue colour changes to green due to the formation of FeSO4 .
9. (a)(i) Blue (ii)White
(b) loss of water in crystalisation.
10.(a) Homogeneous mixture of two or more metals or non- metals mixed in molten
state.
(b) Duralium
(c) solder is an alloy of lead and tin
11. (a) (i) Double displacement
(ii) Combination
(iii) Decomposition
(b) It is a precipitation reaction because precipitates are formed.
12.(i) Materials extracted from ore are called mineral.
(ii) Mineral from which metal is extracted called an ore.
(iii) Impurities present in an ore are called gangue.
13. Glucose (in cytoplasm)--Energy+Pyruvate-------(i) Absence of O2(yeast)>C2H5OH+ CO2+Energy
(ii) Lack of O2(muscle cells)->
Lactic acid + Energy
(iii) Presence of O2(mito.)->CO2+
H2O+ Energy
14. . No the answer is not correct sometimes during vigorous physical work the amount
of oxygen declines in our muscles at this time pyruvate breaks down in insufficient
oxygen and forms lactic acid instead of Carbon dioxide and water.
15.(i)Testosterone (ii) Thyroxine (iii)Abscissic acid (iv) Cytokinin (v)Insulin(vi) growth
hormone
16. (i)Renewable source of energy
(ii) Accessible
(iii) Causes no pollution
(iv)Have no moving parts and requires less maintenance
(b) Availability of Si for making solar cell is limited.
17. 1 volt=1 joule/1 coulomb
Voltmeter
Silver is better conductor since resistivity is less than copper
18. At constant temperature, current flowing through a conductor is directly
proportional to potential difference. Fig.12.2 of P.No. 204
19. (i) Number of coils
(ii) nature of materials
Right hand thumb rule
20. Zn is more reactive than Cu
Tarnishing occurs due to formation of Ag2S
HNO3 is a strong oxidizing agent
To prevent rusting
It is a noble metal
21. Fig 7.1 a P.No. 115
(b) Sharp object-receptor of skin ->sensory nerve-> Spinal cord ->motor nerve->effector
muscle in foot
(Reflex arc)
22. 1. It consists of a piece of wire of alloy having appropriate melting point.
2. transfer of charge from charged body to earth.
3. When the current in the circuit is increased suddenly.
Fuse wire melts and circuit breakdown
23. Fig. 6.30 Page no.110 NCERT
In tubules of nephron
24.(a)Amphoteric oxides are those oxides which show both acids as well as bases to
form salts and water.
Ex: Aluminium metal reacts in this manner with acids and bases.
SnO2 is also an example of amphoteric oxides.
(b) Metals such as Sodium and Potassium are kept immersed is Kerosene
becausethey are very reactive and have high affinity towards oxygen and will violently
react with atmospheric oxygen on contact with air.
(c)
Aluminium reacts readily with steam to give aluminium oxide and hydrogen gas,
the reaction does not always occur. This is due to a thin but strong layer of aluminium
oxide being coated onto the metal, thus preventing it from the reaction. aluminium +
steam aluminium oxide + hydrogen 2Al(s) + 3H2O(g) Al2O3(s) + 3H2(g)
[1]
(d)
(i)
Bromine
(ii)
Iodine
[1]
25. A
26 B
27. A
28. B
29 A
30 D
31 D
32. C
33. C
34. Because acids present in pickles react with the metal .
35. To absorb the CO2 evolved during respiration.
36. Because pure metals gets oxidized and become weak.
SAMPLE PAPER NO 3 (SA1)
Science
Class-X
Time : 3 Hrs.
General Instructions:
MM: 90
1.The question paper comprises of two sections A and B .You have to attempt both the section.
2. All questions are compulsory.
3. Question No. 1 to 3 in section A are one mark question.
4. Question No. 4 to 6 are two marks question, to be answered in about 30 words each.
5. Question No. 7 to 18 are three marks question. To be answered in about 50 words each.
6. Question No.19 to 24 are five marks questions. To be answered in about 70 words each.
7. Question No.25 to 33 in section B are multiple choice based on practical skills. Each question is a one mark
question. You are to choose one most appropriate response out of the four provided to you.
8. Question No. 34 to 36 in section B are practical based and carry 2 marks each.
SECTION – A
Q1. Write the chemical name of Rust & write its formula.
1
Q2. Give one example of a plant part which is positively hydrotropic as well as positively geotropic. 1
Q3. Why are copper wires used as connecting wires?
1
Q4. Why is there so much emphasis on changing over from petrol/diesel driven automobiles to CNG-driven
vehicles? 2
Q5. Cinnabar is an ore of metal X. It exists in the lower order of the reactivity series. Write down the reaction
involved in it for the extraction of X.
2
Q6. Can any source of energy be pollution free? Why or Why not?
Q7. A solution of a substance ‘X’ is used for white washing.
a) Name the substance ‘X’ and write its formula.
b) Write the reaction of the substance ‘X’ with water.
2
(2+1=3)
Q8. A reddish brown metal ‘X’ when heated in the presence of oxygen forms a black compound ‘Y’ which is
basic in nature. When heated with hydrogen gas gives back ‘X’. Identify ‘X’ and ‘Y’. Write down the reactions
involved.
3
Q9. A student took a pale green substance ‘A’ in a test tube and heated it over the flame of a burner. A brown
colored residue ‘B’ was formed along with evolution of two gases with burning smell of sulphur. Identify ‘A’ and
‘B’. Write the chemical reaction involved. 3
Q10. A substance ‘X’ is used in the kitchen for making tasty crispy pakoras and is also an ingredient of antacid.
Name the substance ‘X’
(i) How does ‘X’ help to make cakes and bread soft and spongy?
(ii) Is the pH value of solution ‘X’ lesser than or greater than 7.0?
(1+1+1=3)
Q11. Write the functions of the following in the digestive process:
(i) Bile.
(ii) Bicarbonates secreted by the duodenal wall.
(iii) Pancreatic amylase.
(1+1+1=3)
Q12. How does the plant shoot bends, when the plant is placed in a room having only one open window?
Which type of tropic movement is this?
3
Q13. On touching a hot plate, you suddenly withdraw your hand.
a) Which category of neurons became active first,
b) and which one next?
c) What name is given to the microscopic gap between two adjacent neurons?
(1+1+1=3)
Q14. A wire of length L and resistance R is stretched so that its length is doubled. How will its (a) Resistance
change (b) Resistivity change?
(2+1=3)
Q15. A household uses the following electric appliances:
(i)Refrigerator of rating 400 W for ten hours each day.
(ii) Two electric fans of rating 80 W each for twelve hours each day.
(iii) Six electric tubes of rating 18 W each for 6 hours each day.
Calculate the electricity bill of the household for the month of June if the cost per unit of electric energy is Rs.
3.00.
3
Q16. H2 has been considered as a rocket fuel. Would you consider it as a cleaner fuel than CNG? Why or Why
not?
3
Q17.
Why is the earth pin thicker and longer than the live and the neutral pins? 3
Q18. A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is
a) Pushed into the coil?
b) Withdrawn from inside the coil?
c) Held stationaryinside the coil?
(1+1+1=3)
Q19. Define and Describe with the help of an activity the Ohm’s law. Also draw the appropriate graph.
(4+1=5)
Q20. a) List the properties of magnetic lines of force.
c) Draw magnetic field lines through and around a current carrying solenoid coil. What is its use?
(2+3=5)
Q21. a) Veins and arteries carry blood. Which of these carry blood?
i) Away from the heart?
ii) Back to the heart?
b) Draw a well labeled diagram of human heart.
(2+3=5)
Q22. a)Why is sodium kept immersed in kerosene oil?
b) Write equations for the reactions of
i) Iron with steam.
ii) Calcium and potassium with water.
(2+3=5)
Q23. Compounds such as alcohols and glucose also contain hydrogen but are not categorized as acids.Describe
an Activity to prove it.
(5)
Q24. Draw the structure of a Neuron. Give the function of the following glands
1. Pancreas 2. Thyroid gland 3. Pituitary gland. (2+3)
Section B
Q25) The pH of a solution is 4. It is:
i)
Basic.
ii)
Acidic.
iii)
Neutral.
iv)
Salty.
Q26) Which of the following will turn red litmus to blue litmus?
a) Sulphuric acid
b) lemon juice
hydrochloric acid.
c) sodium hydroxide
Q27) On adding HCI to Zn metal, the gas produced is:
a)hydrogen
b) oxygen
c)chlorine
d) carbondioxide
Q28) Resistance is less when resistors are connected in :
a) Series
b) parallel
c) either series or parallel
d) both series or parallel
Q29) The relation between V-I in a conductor is given by:
a) Ampere.
b) Ohm.
c) Coulomb.
d) Fleming.
Q30) Key is plugged in the circuitonly when readings have to be measured. This is done to stop:
d)
a) Extra temperature
a) Extra energy loss.
.
b) Burning of circuit.
d) All the above.
Q31) In an experiment to show that light is necessary for photosynthesis the plant is kept in dark so that .
a) Chlorophyll is removed from leaves.
b) Leaves are destarched.
c) Both (a) and (b).
d) None of the above.
Q32)Which of the following is present in guard cells:
a) Nucleus.
b) Chloroplast.
c) Both chloroplast and nucleus.
d) None of the above.
Q33) In an experiment to show that light is necessary for photosynthesis which of the following part of the leaf
will become blue-black on adding iodine solution:
a) Uncovered part of leaf.
b) Covered part of leaf.
c) Both (a) and (b).
d) None of the above.
Q34. Why leaves are boiled in alcohol before testing for starch?
Q35. Why copper sulphate becomes colourless on heating?
Q36. How are ammeter and voltmeter connected in an electric circuit?
MODEL ANSWERS 4 (SA1)
KENDRIYA VIDYALAYA SANGATHAN (JAMMU REGION)
SCIENCE (X)
Marking Scheme
MM: 90
Section-A
1. Ferrous oxide Fe2O3
1
2. Roots
1
3. The Electrical Resistivity of copper is low
1
4. CNG on burning produces only carbon dioxide and water. It does not produce smoke. It does not leave
unburned hydro-carbons, lead particulates etc.
2
5. X is mercury and the ore is HgS.
2HgS(s)+3O2(g)---------------------------->2HgO(s)+2SO2(g)
2HgO(s)----------------------------->2Hg(l)+O2(g)
2
7. No source of energy can be called pollution free, because the use of any source of energy disturbs the
environment in one way or the other. The actual source of energy may be pollution free, but the assembly of
the device might have caused some damage to the environment. So, in absolute sense no source of energy can
be called pollution free.
2
8. (a) Calcium Oxide CaO
3
(b) CaO(s) +H2O-------------------------->Ca(OH)2(aq)
Quick lime
(slaked lime)
9. Oxygen reacts with copper to form copper oxide which has black colour
2Cu(s)+O2(g)-------------------> 2CuO(s)
Air
Black
3
CuO+H2----------------->Cu+H2O
The copper oxide is losing oxygen and is being reduced. The hydrogen is gaining oxygen and it being oxidized .
10. 2FeSO4(s) ------------>Fe2O3(s)+SO2(g)+SO3(g)
A (green)
B(brown)
11 2NaHCO3------------------------------------->Na2CO3+H2O+CO2
X(sodium hydrogen carbonate)
(i)
(ii)
3
3
(Sodium Carbonate)
When CO2 gas escapes as bubbles it leaves behind pores which make the cake or bread soft and
spongy.
It is salt of strong base so the pH of the solution will be more than 7.0.
12. (i) Bile- it is secreted by the gall bladder and it emulsifies the fats into the smaller
digestion.
droplets for their easy
(ii) It provides alkaline medium in the duodenum which is needed for the action of pancreatic enzymes of
different food components for their digestion.
(iii) Pancreatic amylase enzymes digests starch and changes it into maltose.
3
13. When a plant is placed in such a room that has only one open window, the shoot of the plant bends
towards the direction of light. Plant hormone auxin is formed that diffuses towards the shady side of the shoot
and stimulates the cells to live longer on the side of the shoot which is away from light. In this way the shoot
bends towards the light.
3
14. On touching a hot plate, first the sensory neurons are activated, which take the information to the brain or
spinal cord. Next, the motor neurons become active and bring the impulses from the brain to the muscles. On
receiving these impulses the muscles contract and the hand is immediately removed from the hot plate.
Synapse.
3
15. (a) If the original length of the wire is I and its cross-sectional area is A, then R=pl/A. When length becomes
21, cross-sectional area reduces to A/2 because volume does not change. The new resistance=p((21)/A/2=4
pl/A=4R
(b) Resistivity does not change.
3
16. Electrical energy consumed per day =400X10+2X80X12+6X18X6
=4000+1920+648
=6568Wh
=6.568 kWh
Electrical energy consumed in 30 days =6.568X30
=197 kWh (units)
Electrical Bill =197X3
=Rs. 591.
3
17. Hydrogen when burned in presence of oxygen produces water as the only product with release of heat and
energy. Water does not cause any damage to environment while CNG during burning produces CO 2 and H2O.
CO2 is not a pollutant yet it leads to rise in the temperature (global warming), this rise is called green- house
effect and this will affect polar ice and life on the earth is at risk. Thus hydrogen is cleaner fuel than CNG.
3
18 It is thicker so that it does not enter into the live or neutral sockets. It is made longer so that it gets
connected to the earth terminal earlier than the live and neutral pins. This ensures the safety of the user.
3
19. Activity 12.1 of NCERT Book
Figure 12.3 of NCERT Book
5
20.(a) Any two properties
(b)
Figure 13.10 of NCERT Book
5
21. a) 1.Arteries carry blood away from the heart.
2. Veins carry blood back to the heart
5
(b) Figure 6.10 of NCERT Book
22. a) Sodium reacts with oxygen at room temperature
(b) correct equations
5
23. Activity 3.13 of NCERT Book
24. Correct diagram & Function.
Section B
25.
ii
26.
C
27.
A
28.
B
29.
B
30.
D
31.
B
32.
C
33.
A
Time: 3 Hrs.
SAMPLE PAPER NO 5 (SA1)
Class-X (Science)
SA –I (2015-2016)
MM: 90
General Instructions:
1. The question paper comprises of two sections A and B .You are to attempt both the
section.
2. All questions are compulsory.
3. Question No. 1 to 3 in section A are one mark question.
4. Question No. 4 to 6 are two marks question, to be answered in about 30 words each.
5. Question No. 7 to 18 are three marks question. To be answered in about 50 words
each.
6. Question No.19 to 24 are five marks questions. To be answered in about 70 words
each.
7. Question No.25 to 33 in section B are multiple choice based on practical skills. Each
question is a one mark question. You are to choose one most appropriate response out
of the four provided to you.
8. Question No. 34 to 36 in section B are practical based and carry 2 marks each.
SECTION – A
Q1.In which biochemical forms the Photosynthetic products moves in phloem tissue?
Q2. Name the metal which stored in kerosene?
Q3. Why are copper wires used as connecting wires?
Q4. Royal water is prepared by mixing two acids ‘A’ and ‘B’ .Identify ‘A’ and ‘B’. What is
the ratio in which these two acids are mixed?
Q5. Write the composition of CNG and LPG.
Q6. Cinnabar is an ore of metal X. It exists in the lower order of the reactivity series.
Write down the reaction involved in it for the extraction of X.
Q7. Can any source of energy be pollution free? Why or Why not?
Q8.Silver on the exposure of light react with Bromine and formed Silver bromide .
Write the chemical equation and balance it.
Q9. Name the part of Digestive system
i)
Water absorbed from Unabsorbed food .
ii)
Secretes bile juice.
*Q10. A solution of a substance ‘X’ is used for white washing.
d) Name the substance ‘X’ and write its formula.
e) Write the reaction of the substance ‘X’ with water.
*Value based Question
Q11. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with
respect to their structure and functioning.
Q12. A student took a pale green substance ‘A’ in a test tube and heated it over the
flame of a burner. A brown colored residue ‘B’ was formed along with evolution of two
gases with burning smell of sulphur. Identify ‘A’ and ‘B’. Write the chemical reaction
involved.
Q13.A substance ‘X’ is used in the kitchen for making tasty crispy pakoras and is also an
ingredient of antacid. Name the substance ‘X’
(i) How does ‘X’ help to make cakes and bread soft and spongy?
(ii) Is the pH value of solution ‘X’ lesser than or greater than 7.0?
*Value based Question
Q14
Metals
Iron (II)
Copper (II)
Zinc sulphate Silver nitrate
sulphate
sulphate
A
No reaction
displacement
B
displacement
No reaction
C
No reaction
No reaction
No reaction
displacement
Use the table above to answer following questions about metals A,B and C
i)
Which is the most reactive metal?
ii)
Which would you observe if B is added to a solution of FeSO4 ?
iii)
Arrange the metals A,B and C in the order of increasing reactivity.
Q15. On touching a hot plate, you suddenly withdraw your hand.
d) Which category of neurons became active first,
e) and which one next?
f) What name is given to the microscopic gap between two adjacent neurons?
.Q16
?
. For the circuit shown in the diagram given above :
(a) the value of current through each resistor
(b) the total current in the circuit
(c) the total effective resistance of the circuit.
Q17.Differenciate between Renewable and non- renewable ( Any 3 )
.
Q18. A household uses the following electric appliances:
(i)Refrigerator of rating 400 W for ten hours each day.
(ii) Two electric fans of rating 80 W each for twelve hours each day.
(iii) Six electric tubes of rating 18 W each for 6 hours each day.
Calculate the electricity bill of the household for the month of June if the cost per unit
of electric energy is Rs. 3.0
19 a) Veins and arteries carry blood. Which of these carry blood
i) Away from the heart?
ii) Back to the heart?
b) Draw a well labeled diagram of human heart.
Q20 A student wrongly draws the given circuit diagram for verification of
ohm’s law. Assume that voltmeter and milliammeter are perfect/ ideal in
nature.
Answer the following questions on the circuit diagrams ;
(i)
(ii)
What will be the voltmeter readings in this case and why ?
Point out two major mistakes made by the student in drawing the
circuit diagram.
iii) Re-draw the circuit diagram correctly
Q 21
a) List the properties of magnetic lines of force.
b) Draw magnetic field lines through and around a current carrying solenoid coil.
What is its use?
(2+3=5)
Q22
a) Show the formation of MgO by the transfer of electrons.
b) Why do ionic compounds have high melting points?
(2+3=5)
Q 23 Five solutions A, B ,C, D and Ewhen tested with universal indicator showed pH
as 4,1,11,7 and 9,
respectively. Which solution is
a) neutral
b) Strongly alkaline?
c) Strongly acidic?
d) Weakly acidic?
e) Weaklyalkaline?
Arrange the pH in increasing order of hydrogen- ion concentration.
Q 24(a) Draw a neat diagram of human respiratory system and label the parts
and label 9 parts in it.
(b) What are the end products of digestion of fat and protein in human
beings ?
Section B
Q25) The pH of a solution is 10 It is:
v)
Basic.
vi)
Acidic.
vii) Neutral.
viii) Salty.
Q26)The gas produced on adding sodium carbonate in acids :
a) hydrogen
b) oxygen c) carbondioxide d) carbonmonoxide
.
Q27) Resistance is less when resistors are connected in :
e) Series
f) parallel
g) either series or parallel
h) both series or parallel
28) The relation between V-I in a conductor is given by:
e) Ampere.
f) Ohm.
g) Coulomb.
h) Fleming.
Q29 )On mixing the aqueous solutions of sodium sulphate and barium chloride the
color of the precipitate formed is:
a) Black
c) Brown
b) Green.
d) White.
Q30) The color of metal deposited when iron nails are dipped in aqueous solution of
copper sulphateis :
b) Reddish brown.
b) silvery white.
c) Grey.
d) Green.
.
.
Q31) If four 2 ohm resistors are connected in series then the effective resistance of the
combination is:
i)
2 ohm.
ii)
8 ohm.
iii)
0.5 ohm.
iv)
4 ohm.
Q32) In the experiment to show that carbon dioxide is produced during respiration the
role of KOH is to absorb:
a) Carbon dioxide.
b) Nitrogen.
c) Water vapors.
d) Oxygen.
Q33) In the experiment to show that carbon dioxide is produced during respiration the
seeds taken in the flask are:
a) Germinating.
c) Non germinating.
b) Dry.
d) Brown.
34 What meant by pH scale write its range
35 What is meant by destarching restarching of leaf
.
.36 Write the color of wires used in domestic purpose
.
MODEL ANSWERS 5 (SA1)
KENDRIYA VIDYALAYA SANGATHAN (JAMMU REGION)
SCIENCE (X)
Marking Scheme
MM: 90
Section-A
1. Sucrose
1
2. Na/K
1
3. The Electrical Resistivity of copper is low
1
4. 3HCL : HNO3
2
5. CNG – methane LPG – propane and butane.
2
6. X is mercury and the ore is HgS.
2HgS(s)+3O2(g)---------------------------->2HgO(s)+2SO2(g)
2HgO(s)----------------------------->2Hg(l)+O2(g)
2
7. No source of energy can be called pollution free, because the use of any source of
energy disturbs the environment in one way or the other. The actual source of energy
may be pollution free, but the assembly of the device might have caused some damage
to the environment. So, in absolute sense no source of energy can be called pollution
free.
3
8 Ag + Br2 ------- 2AgBr
3
.9 i)large intestine ii ) liver
10 (a) Calcium Oxide CaO
3
(b) CaO(s) +H2O-------------------------->Ca(OH)2(aq)
Quick lime
.
. 11
(slaked lime)
Structure
Functioning
Lungs
Alveoli are balloon like
structure
Having extensive network
of blood vessels
Exchange of gases
Nephrons
Cup shaped structure
followed by tubule along
blood vessles
Filtration and
reabsorption
12. 2FeSO4(s) ------------>Fe2O3(s)+SO2(g)+SO3(g)
A (green)
B(brown)
13 2NaHCO3------------------------------------->Na2CO3+H2O+CO2
X(sodium hydrogen carbonate)
(iii)
(iv)
3
3
(Sodium Carbonate)
When CO2 gas escapes as bubbles it leaves behind pores which make the cake
or bread soft and spongy.
It is salt of strong base so the pH of the solution will be more than 7.0.
14 i) B.
ii) B displaces Fe from FeSO4.
iii) C< A< B. 3
15. On touching a hot plate, first the sensory neurons are activated, which take the
information to the brain or spinal cord. Next, the motor neurons become active and
bring the impulses from the brain to the muscles. On receiving these impulses the
muscles contract and the hand is immediately removed from the hot plate.
Synapse.
3
16. For the circuit shown in the diagram given below :
(a) the value of current through each resistor
(b) the total current in the circuit
(c) the total effective resistance of the circuit.
17 Any 3 correct difference
.
3
.
18 Electrical energy consumed per day =400X10+2X80X12+6X18X6
=4000+1920+648
=6568Wh
=6.568 kWh
Electrical energy consumed in 30 days =6.568X30
=197 kWh (units)
Electrical Bill =197X3
=Rs. 591.
3
19
b) The blood passes through the heart twice. Right side of the heart receives
deoxygenated blood which is circulated to lungs for purification. At the same time the
left side of the heart receives oxygenated blood which is circulated to the body. This is
called double circulation.
3+ 2= 5
.20 The reading of voltmeter as well as ammeter will be nearly zero. This is due to the
reason that the voltmeter has a very large resistance. Since it is connected in a series
in a circuit, the current flowing in the circuit will be nearly zero.
(ii) (a) Voltmeter is connected in series and ammeter is connected in parallel.
(b) ‘+’ and ‘-‘ terminals of a as well as ammeter are connected wrongly.
(iii)
1+1+3 = 5
.
21
..
.b )No two field lines are found to cross each other. If they did, it would mean that at
the point of intersection , the compass needle would point towards two directions,
which is not possible.
b) Figure 13.8 of NCERT Book
correct definition of rule
(a)The main function performed by the glomeruli is selective filtration . They filter small
molecules containing glucose, salt, urea and liquid serum etc. The large molecules such
as proteins remain in blood. Thus, glomeruli of the kidneys function as dialysis bags.
b) Figure 6.14 of NCERT Book
2 + 3=5
22.
a) Correct formation by dot representation method.
b) Correct explanation.
3+2=5
23. ( a) Activity 3.13 of NCERT Book
(i)
D
(ii)
C
(v)
B
(vi)
A
(vii)
E
Correct increasing order.
1X5=5
24 Human respiratory system
(b)
Fat : fatty acid + glycerol
Protein : amino acids
3+2= 5
Section B
25.
1
26.
c
27.
b
28.
b
29.
d
30.
a
31.
2
32.
a
33.
a
1x9=9
34 correct explanation
2
35 correct explanation 2
36 Red – live
Green – earth Black – neutral 2
SAMPLE PAPER NO 8 (SA-I)2015-16
Subject- Science
Time :- 3Hrs.
Class –X
Maximum Marks 90
General Instructions:
a) All questions are compulsory.
b) The question paper comprises of two sections, A and B. You are to attempt both the sections.
c) Questions 1 to 3 in section A are one mark questions. These are to be answered in one word or
in one sentence.
d) Questions 4 to 6 in section A are two marks questions. These are to be answered in about 30
words each.
e) Questions 7 to 18 in section A are three marks questions. These are to be answered in about 50
words each.
f) Questions 19 to 24 in section A are five marks questions. These are to be answered in about 70
words each.
Questions 25 to 27 in section B are 2 marks questions and Questions 28 to 36 are multiple choice
questions based on practical skills. Each question of multiple choice questions is a one mark question.
You are to select one most appropriate response out of the four provided to you
SECTION-A
Q1. Why Calcium metal after reaction with water starts floating on its surface?
1
Q2. The potential difference across the terminals of a cell is 1.5V.It is connected with a
resistance of 30 ohm. Calculate the current flowing through the circuit
1
Q3. Name two types of Biogas plants.
1
Q4. Royal water is prepared by mixing two acids ‘A’ and ‘B’ .Identify ‘A’ and ‘B’. What is the
ratio in which these two acids are mixed?
2
Q5. Why is there so much emphasis on changing over from petrol/diesel driven
automobiles to CNG-driven vehicles? 2
Q6. Cinnabar is an ore of metal X. It exists in the lower order of the reactivity series. Write
down the reaction involved in it for the extraction of X.
2
Q7. Can any source of energy be pollution free? Why or Why not?
*Q8. A solution of a substance ‘X’ is used for white washing.
f) Name the substance ‘X’ and write its formula.
g) Write the reaction of the substance ‘X’ with water.
3
(2+1=3)
Q9. A reddish brown metal ‘X’ when heated in the presence of oxygen forms a black
compound ‘Y’ which is basic in nature. When heated with hydrogen gas gives back ‘X’.
Identify ‘X’ and ‘Y’. Write down the reactions involved.
3
Q10. A student took a pale green substance ‘A’ in a test tube and heated it over the flame
of a burner. A brown colored residue ‘B’ was formed along with evolution of two gases
with burning smell of sulphur. Identify ‘A’ and ‘B’. Write the chemical reaction involved.
3
*Q11.A substance ‘X’ is used in the kitchen for making tasty crispy pakoras and is also an
ingredient of antacid. Name the substance ‘X’
(i) How does ‘X’ help to make cakes and bread soft and spongy?
(ii) Is the pH value of solution ‘X’ lesser than or greater than 7.0?
(1+1+1=3)
Q12. Write the functions of the following in the digestive process:
(i) Bile.
(ii) Bicarbonates secreted by the duodenal wall.
(iii) Pancreatic amylase.
(1+1+1=3)
Q13.How does the plant shoot bends, when the plant is placed in a room having only one
open window? Which type of tropic movement is this?
3
Q14. On touching a hot plate, you suddenly withdraw your hand.
g) Which category of neurons became active first,
h) and which one next?
i) What name is given to the microscopic gap between two adjacent neurons?
(1+1+1=3)
Q15. A wire of length L and resistance R is stretched so that its length is doubled. How will
its (a) Resistance change (b) Resistivity change?
(2+1=3)
Q16. A household uses the following electric appliances:
(i)
Refrigerator of rating 400 W
for ten hours each day.
(ii) Two electric fans of rating 80 W each for twelve hours each day.
(iii) Six electric tubes of rating 18 W each for 6 hours each day.
Calculate the electricity bill of the household for the month of June if the cost per unit of
electric energy is Rs. 3.00.
3
Q17.H2 has been considered as a rocket fuel. Would you consider it as a cleaner fuel than
CNG? Why or Why not?3
Q18.Why is the earth pin thicker and longer than the live and the neutral pins? 3
Q19.i A coil of insulated copper wire is connected to a galvanometer. What would happen
if a bar magnet is
d) Pushed into the coil?
e) Withdrawn from inside the coil?
f) Held stationaryinside the coil?
ii-State flaming right hand rule .
Q20 Define and Describe with the help of an activity the Ohm’s law. Also draw the
appropriate graph.
(4+1=5)
Q21. a)”Two magnetic lines of force never intersect each other”. Comment.
b) Draw magnetic field lines around a current carrying circular coil. Define Right hand
thumb rule.
(2+3=5)
Q22. a) Why are glomeruli considered as dialysis bags?
b)Draw a well labeled diagram of a nephron.
(2+3=5)
Q23. a)Why is sodium kept immersed in kerosene oil?
b) Write equations for the reactions of
i) Iron with steam.
ii) Calcium and potassium with water.
(2+3=5)
Q24 Five solutions A, B ,C, D and Ewhen tested with universal indicator showed pH as
4,1,11,7 and 9, respectively. Which solution is
a) neutral
b) Strongly alkaline?
c) Strongly acidic?
d) Weakly acidic?
e) Weaklyalkaline?
Arrange the pH in increasing order of hydrogen- ion concentration.
(5)
Section B
Q25.A student took the following samples to find out their pH using pH paper ,dilute
hydrochloric acid , lemon juice,washing soda and soap solution .The teacher remarked that
one of the samples , when taken was not proper . To which sample was the teacher
referring to ?
Q26.What will happen if a student while studying the dependence of current on the
potenitial difference keeps the circuit closed for a long time to measure the current and
potential difference .
Q.27.While doing the experiment to show light is necessary for photosynthesis the student
was given following substances by his fellow students .which are the correct suggestion
given by his fellow students?
i.Safranine should be used instead of Iodine .
ii.The leaf should be boiled in alcohol with water bath to remove chlorophyll.
iii.the transparent paper strip should be used instead of black paper strip .
iv .The plant should be destrached before starting the experiment .
Q28) The pH of a solution is 4. It is:
ix)
Basic.
x)
Acidic.
xi)
Neutral.
xii) Salty.
Q29) Which of the following will turn red litmus to blue litmus?
b) Sulphuric acid
b) lemon juice
d) hydrochloric acid.
c) sodium hydroxide
Q30)The gas produced on adding sodium carbonate in acids :
b) hydrogen
b) oxygen c) carbondioxide d) carbonmonoxide
Q231) On adding HCI to Zn metal, the gas produced is:
a)hydrogen
b) oxygen
c)chlorine
d) carbondioxide
Q32) Resistance is less when resistors are connected in :
i) Series
j) parallel
k) either series or parallel
l) both series or parallel
Q33) in a circuit ammeter is always connected in :
a) Series
b) parallel
c) either series or parallel
d) both series or parallel
Q34) The relation between V-I in a conductor is given by:
i) Ampere.
j) Ohm.
k) Coulomb.
l) Fleming.
Q35)On mixing the aqueous solutions of sodium sulphate and barium chloride the color of
the precipitate formed is:
b) Black
c) Brown
b) Green.
d) White.
Q36) The color of metal deposited when iron nails are dipped in aqueous solution of
copper sulphateis :
d) Reddish brown.
b) silvery white.
e) Grey.
d) Green.
MODEL ANSWERS 4 (SA1)
SCIENCE (X)
Marking Scheme
MM: 90
Section-A
1. Correct reason
1
2. I = 0.05A
1
3. i. Fixed dome type ii. Floating gas holder type
4. 3HCL : HNO3
½+ 1/2
2
5. CNG on burning produces only carbon dioxide and water. It does not produce smoke. It
does not leave unburned hydro-carbons, lead particulates etc.
2
6. X is mercury and the ore is HgS.
2HgS(s)+3O2(g)---------------------------->2HgO(s)+2SO2(g)
2HgO(s)----------------------------->2Hg(l)+O2(g)
2
7. No source of energy can be called pollution free, because the use of any source of
energy disturbs the environment in one way or the other. The actual source of energy may
be pollution free, but the assembly of the device might have caused some damage to the
environment. So, in absolute sense no source of energy can be called pollution free.
2
8. (a) Calcium Oxide CaO
3
(b) CaO(s) +H2O-------------------------->Ca(OH)2(aq)
Quick lime
(slaked lime)
9. Oxygen reacts with copper to form copper oxide which has black colour
3
2Cu(s)+O2(g)-------------------> 2CuO(s)
Air
Black
CuO+H2----------------->Cu+H2O
The copper oxide is losing oxygen and is being reduced. The hydrogen is gaining oxygen
and it being oxidized .
10. 2FeSO4(s) ------------>Fe2O3(s)+SO2(g)+SO3(g)
A (green)
3
B(brown)
11 2NaHCO3------------------------------------->Na2CO3+H2O+CO2
X(sodium hydrogen carbonate)
3
(Sodium Carbonate)
(viii) When CO2 gas escapes as bubbles it leaves behind pores which make the cake or
bread soft and spongy.
(ix) It is salt of strong base so the pH of the solution will be more than 7.0.
12. (i) Bile- it is secreted by the gall bladder and it emulsifies the fats into the smaller
droplets for their easy digestion.
(ii) It provides alkaline medium in the duodenum which is needed for the action of
pancreatic enzymes of different food components for their digestion.
(iii) Pancreatic amylase enzymes digests starch and changes it into maltose.
3
13. When a plant is placed in such a room that has only one open window, the shoot of the
plant bends towards the direction of light. Plant hormone auxin is formed that diffuses
towards the shady side of the shoot and stimulates the cells to live longer on the side of
the shoot which is away from light. In this way the shoot bends towards the light.
3
14. On touching a hot plate, first the sensory neurons are activated, which take the
information to the brain or spinal cord. Next, the motor neurons become active and bring
the impulses from the brain to the muscles. On receiving these impulses the muscles
contract and the hand is immediately removed from the hot plate.
Synapse.
3
15. (a) If the original length of the wire is I and its cross-sectional area is A, then R=pl/A.
When length becomes 21, cross-sectional area reduces to A/2 because volume does not
change. The new resistance=p((21)/A/2=4 pl/A=4R
(b) Resistivity does not change.
3
16. Electrical energy consumed per day =400X10+2X80X12+6X18X6
=4000+1920+648
=6568Wh
=6.568 kWh
Electrical energy consumed in 30 days =6.568X30
=197 kWh (units)
Electrical Bill =197X3
=Rs. 591.
3
17. Hydrogen when burned in presence of oxygen produces water as the only product with
release of heat and energy. Water does not cause any damage to environment while CNG
during burning produces CO2 and H2O. CO2 is not a pollutant yet it leads to rise in the
temperature (global warming), this rise is called green- house effect and this will affect
polar ice and life on the earth is at risk. Thus hydrogen is cleaner fuel than CNG.
3
18 It is thicker so that it does not enter into the live or neutral sockets. It is made longer so
that it gets connected to the earth terminal earlier than the live and neutral pins. This
ensures the safety of the user.
3
19.(i) Due to change in magnetic flux linked with coils, the galvanometer shows
deflection(say towards right).
(ii) Due to the change in magnetic flux linked with coil, the galvanometer shows
deflection (say towards left opposite to that in case i)
(iii) As it is stationary no change in magnetic flux linked with coil, so galvanometer shows
no deflection.
leming's right hand rule (for generators) shows the direction of induced current when a conductor moves
in a magnetic field.
The right hand is held with the thumb, first finger and second finger mutually perpendicular to each other (at
right angles), as shown in the diagram .

The Thumb represents the direction of Motion of the conductor.

The First finger represents the direction of the Field. (north to south)

The Second finger represents the direction of the induced or generated Current (the direction of the
induced current will be the direction of conventional current; from positive to negative).

One particular way of remembering the rule is the "FBI" acronym for Force (or otherwise motion), B as
the magnetic field sign and I as the current. The subsequent letters correspond to subsequent fingers,
counting from the top. Thumb -> F; First finger -> B; Second finger -> I

There is also a Fleming's left hand rule (for electric motors). The appropriately handed rule can be
recalled from the letter "g", which is in "right" and "generator".
5
20. Activity 12.1 of NCERT Book
Figure 12.3 of NCERT Book
5
21.a) No two field lines are found to cross each other. If they did, it would mean that at the
point of intersection , the compass needle would point towards two directions, which is
not possible.
b) Figure 13.8 of NCERT Book
correct definition of rule
5
22. (a)The main function performed by the glomeruli is selective filtration . They filter
small molecules containing glucose, salt, urea and liquid serum etc. The large molecules
such as proteins remain in blood. Thus, glomeruli of the kidneys function as dialysis bags.
b) Figure 6.14 of NCERT Book
5
23. a) Sodium reacts with oxygen at room temperature
(b) correct equations
24. (i)
5
D
(ii)
C
(x)
B
(xi)
A
(xii)
E
Correct increasing order.
Section B
25.
ii
26.
c
27.
c
28.
a
29.
b
30.
a
31.
b
32.
d
33.
a
34.The teacher was referring to washing soda because it is in powder form not in liquid
form .To find pH using pH paper the sample should be in liquid form .
35.If The circuit is kept closed for a long time t ,resistor will get heated up and its value will
change ,this is because heat produced any resistor
H=I2 Rt
As time will increase heat produced will increase .
36.suggestions ii and iv are correct .
SAMPLE PAPER NO 4(SA1)
Class –X
Subject- Science
Time : 3hrs
Maximum Marks: 90
General Instructions:
1.The question paper comprises of two sections A and B .You are to attempt both the section.
2. All questions are compulsory.
3. There is no overall choice. However, internal choice has been provided in all the five questions of five marks
category. Only one option in each question is to be attempted.
4. All questions of section A and all questions of section B are to be attempted separately.
5. Question No. 1 to 3 in section A are one mark question. These are to be attempted separately.
6. Question No. 4 to 6 are two marks question, to be answered in about 30 words each.
7. Question No. 7 to 18 are three marks question. To be answered in about 50 words each.
8. Question No.19 to 24 are five marks questions. To be answered in about 70 words each.
9. Question No.25 to 33 in section B are multiple choice based on practical skills. Each question is a one mark
question. You are to choose one most appropriate response out of the four provided to you.
10. Question No.34 to 36 are two marks questions which are on practical based. To be answered in 30 words.
11. An additional 15 minutes time has been allotted to read this question paper only and will not write any
answer script during the period.
Section A
Q.1. write an example of a neutralization reaction? (1)
Q.2. Name the juice secreted by liver? (1)
Q.3. Why is sodium kept immersed in Kerosene oil? (1)
Q.4. Write any two causes that may damage the kidney of a person? (2)
Q.5. Write observation with reaction for the following : Granulated zinc reacts with dil. sulphuric acid ?
(2)
Q.6. What is meant by the term magnetic field lines? List any two properties of magnetic field
lines?
(2)
Q.7. Write the Names and chemical formulae of the products formed by heating gypsum at 373 K.?
(3)
Q.8. Differentiate between renewable and non-renewable sources of energy with one example
for each? (3)
Q.9. Define neutralization reactions? Give an example in daily life application ? (3)
Q.10. Give 1 example for each of the following reactions
(a) Combination reaction
(b) Decomposition reaction
(c) Displacement reaction
(3)
Q.11. Why does distilled water not conduct electricity whereas rain water does?
(3)
Q.12. .When water is added to a white powder ‘A’ vigorous reaction takes place & a large amount of
heat is released. ‘A’ is also used for white washing? (3)
Q.13. Which organ secretes a hormone when blood sugar rises in our body? Name the hormone and
name one enzyme released by this organ? (3)
Q.14. Draw human excretory system and label
(5) Left Kidney
(6) Ureter
(7) Urinary bladder
(8) Urethra
(3)
Q.15. (a) Define 'water of crystallization?
(b) Give two examples of substances having water of crystallization. Write their chemical
formula also.
(3)
Q.16. A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar
magnet is
g) Pushed into the coil?
h) Withdrawn from inside the coil?
i) Held stationary inside the coil?
(3)
Q.17. Write one feature which is common to each of the following pairs of terms:
(i) Glycogen and starch
(ii) Chlorophyll and haemoglobin
(iii) Arteries and veins
(3)
Q.18 (a) State two factors on which the strength of magnetic field due to current carrying
conductor depends?
(b) Which rule is used to find the direction of magnetic field due to a straight current
carrying conductor?
(3)
Q.19. Name the product formed in each case when
(1) Hydrochloric acid reacts with sodium hydroxide(aq)
(2) Cl2 reacts with slaked lime
(3) Carbon dioxide is passed through lime water
(4) Zinc(s) reacts with Hydrochloric acid(l)
(5) Sodium Bicarbonate (s) is heated
Or
(5)
Give reasons for the following
(6) Zinc can displace copper from copper sulphate solution
(7) Silver articles become black after sometime when exposed to air
(8) H2 gas is not evolved when most metals react with HNO3
(9) We apply paint on iron grills
(10)
We use gold in jewellery
Q.20. (a) Give an example of a metal which
(i) Can be easily cut with a knife.
(ii) is liquid at a room temperature.
(b) Write chemical equation for the reaction when ?
(i) Steams acts on red hot iron. (ii) Zinc is added to iron sulphate solution.
(c) What are alloys?
(d) Why is food can coated with tin and not zinc?
(5)
Or
What is resistance of the conductor’s .Name two metals which offer very high resistance and two
metals which offer very low resistance .Name the factor on which resistance of the conductors
depends?
Q.21.(a) Explain in brief the mechanism of circulation of blood in human body?
(b) Lymph is another type of fluid involved in transportation. Justify the statement by two
reasons.
OR
(a) Explain the excretory system in human beings.(see fig.6.13 page no.110 NCERT textbook)
(b) List any two strategies used by plants for excretion.
(5)
Q.22. (a) Write a short note on
(1) Fuse
(5)
(2) Earthling
(b) What is short circuit? what happens if a domestic circuit is short circuited
Or
A current carrying wire is placed in east west direction. What will be the direction of force
experienced by it due to a particular perpendicular magnetic field (external). How will the
force be affected on?
(i)
(ii)
Doubling the magnitude of current
Reversing the direction of current through the wire
Q.23. (a) Give short answer:
i) What is the role of auxin in plants?
ii) Where in plants, the hormone cytokines could be present?
iii) What is the role of absasic acid in plants?
(b)Write the parts of central nervous system?
(5)
c) Involuntary actions are controlled by which part of brain.
Or
(i) Name any one sex hormone.
(ii) Which part of nervous system performs reflex actions.
(iii) Which hormone helps in lowering the level of glucose in blood of human
beings?
(iv) Write the function of hormone thyroxin in our bodies.
(v) A polled plant is made to lie horizontally on the ground which part of the
plant will show:
i) Positive geotropism
ii) negative geotropism
Q.24. a) State and explain Fleming’s right hand rule about the direction of induced
current.
a) State the safety devices and precautions to be used in domestic circuits. (Any
three).
(2 + 3 =5)
Or
a) Two circular coils A & B are placed closed to each other. If the current in the
coil A is changed, will some current be induced in coil B? Give reason.
b) Name the rule to determine the direction of a:
(i) Magnetic field produced around a straight conductor carrying conductor.
(ii) Force experienced by a current carrying conductor placed in a magnetic
field, which is perpendicular to it.
(iii) Current induced in a coil due to its rotation in a magnetic field.
Section B
Q25. A solution has pH4. The solution will be
(c) Neutral
(d) Acidic
(c) Basic
(d) Ionic
Q26. What will be the pH of a basic solution
(a) pH>7
(b) pH=7
(1)
(1)
(c) pH < 7
(d) pH=0
Q27.If pH of solution changes from 3 to 4 , the solution becomes
(a) less acidic
(b) Basic
(1)
(c) More acidic
(d) Strongly basic
Q.28.Which gas is evolved in the reaction of Zinc metal and NaOH (1)
(c) Cl2
(d) N2
(c)O2
(d) H2
Q.29.Name the scientist who proposed acid- Base theory
(1)
(a)Arrhenius
(c) Dalton
(b) Newton
(d) Einstein
Q.30.Name the gas evolved when Zinc metal reacts with HCl acid (1)
(a) CO
(b) CO2
(c) SO2
(d)H2
Q.31. What is the important property of an acid?
(a) Sour taste
(b) Soapy touch
(1)
(c) Bitter Taste
(d) No odour
Q.32. A blue litmus paper was first dipped in dil. HCl and then in dil. NaOH solution.
Itwas observed that the colour of the litmus paper
(1)
(a) Changed to red
(b) Changed first to red and then to blue
(c) Changed blue to colourless
(d) Remained blue in both the solutions
Q.33.Mathematically form of ohm’s law is:
(c) R=1/V
(d) R= V/I
(1)
(c) V= I/R
(d) None of above
Q.34. Find out the following in the electric circuit given in the figure-
(a) Potential difference across 4 ohm resistance
(b) Difference in ammeter reading if any of A1 & A2
(2)
Q.35. State Ohm’s Law? How this law can be verified experimentally?
(2)
Q.36. What happens when an iron nail is put inside copper sulphate solution? Write
reaction with observation.
(2)
ANSWERKEY
SAMPLE PAPER NO 4(SA1)
Section –A
1. HCl + NaOH
NaCl + H2O + Energy
2. Bile
3. Because sodium reacts vigorously with oxygen at room temperature
4. (i) Kidney infection or injury to kidneys.
(ii) Restricted blood flow to kidneys.
5. Bubbles are seen to come out.
Zn + dil H2SO4  ZnSO4 +H2
6. The field lines which emerges from north and merges at south
(i) They never intersect each other
(ii) They have maximum strength at poles.
7. Plaster of paris, CaSO4.1/2 H2O
8. Energy sources that can be regenerated are called renewable sources of energy.
Eg : Solar energy.
Energy sources that will get depleted someday are called nonrenewable sources of energy.
Eg : Fossil fuels
9. Reaction between acid & base gives salts & water and release energy that is
Neutralization.
Reaction: HCl + NaOHH2O + NaCl + Energy
Antacid (Mg(OH)2) is used to cure acidity in stomach.
10. (a) Combination reaction 2Mg + 02  2MgO
(b) Decomposition reaction CaCO3 CaO + CO2
(c) Displacement reaction Zn + CuSO4  ZnSO4 + Cu
11. Distilled water is pure water and it does not form ions. Whereas rain water contains impurities in it like acid
which contains ions and release them when dissolved in water. Hence no ions in distilled water, so electricity is
not conducted but ions are there is rain water so electricity is conducted.
12. A is calcium oxide CaO
CaO +H2O---Ca (OH)2
13. (i)Pancreas
(ii)Insulin
(iii)trypsin/lipase
14. Fig. 6.30 Page no.110 NCERT
15. (a) Water of crystallisation is the number of water molecules that combine chemically in
definite molecular proportion, with the concerned salt in the crystalline state.
(b) Two correct examples are:
Copper sulphate ,chemical formula = CuSO4.5H2O
Washing soda, chemical name = Na2CO3.10 H2O.
16. (i) Due to change in magnetic flux linked with coils, the galvanometer shows
deflection(say towards right).
(ii) Due to the change in magnetic flux linked with coil, the galvanometer shows
deflection (say towards left opposite to that in case i)
(iii) As it is stationary no change in magnetic flux linked with coil, so galvanometer
shows no deflection.
17. (i) Glycogen and starch – Both are carbohydrates and stored food products.
(ii) Chlorophyll and haemoglobin – Both are pigments.
(iii) Arteries and veins – Both are blood vessels.
18. (a)(i) Number of coils
(ii) nature of materials
(b)Right hand thumb rule
19. 1. NaCl (aq) and water
2. CaOCl2
3. CaCO3
4. ZnCl2 and H2
5. Na2CO3, H2O and CO2
OR
1.Zn is more reactive than Cu
2.Tarnishing occurs due to formation of Ag2S
3.HNO3 is a strong oxidizing agent
4.To prevent rusting
5.It is a noble metal
20. (a) (i)Sodium can be cut with a knife
(ii) Mercury is liquid at room temprature
(b) (i) 3 Fe(s) + 4H2O(g)  Fe2O3 + 4H2(g)
(ii) Ze(s) + FeSO4(aq)  ZnSO4(aq) + Fe(s)
(c) Alloys are homogeneous mixture of two or more than two metals and metals and nonmetals.
(d) Food cans are coated with tin and not zinc because tin is less reactive than zinc and does not
corrode easily and it is cheaper
or
Resistance:
it is the property of a conductor to resist the flow of charges through it. Its S.I. unit is ohm . Two
metals with less resitance are silver and cooper.
Two metals which offer high resistance are mercury and manganese
Factors on which resistance of a conductor depend are length of the conductor area of cross-section
and material
21. A )
(b) 1. It drains tissue fluid from the extra cellular space back into blood.
2. it takes lymphocytes and antibodies from the lymph nodes to the blood.
3. Some of the fluid from digestive tract is absorbed in the lymph and store the fluid
Temporarily.
OR
DIAGRAM OF EXCRETORY SYSTEM
B) 1. Transpiration
2. Bark formation
3. Stomata (gas exchange)
22. 1. It consists of a piece of wire of alloy having appropriate melting point.
2. Transfer of charge from charged body to earth.
3. When the current in the circuit is increased suddenly.
Fuse wire melts and circuit breakdown
OR
The direction of force will be the north direction of wire .
Doubling the magnitude of current , the force acting will be doubled.
The direction of force will be reversed i.e. in the south direction.
23. (a) (i) It is responsible for elongation of plant, bending of shoot towards light etc.
ii) Cytokine promote cell division it is present in greater concentration in areas of rapid
cell division, such as in fruits and seeds.
iii) Absusic acid in plants in habits growth.
b) Central nervous system consists of brain and spinal cord.
c) They are controlled by medulla ablongata.
(5)
Or
i) Estrogen or Testosterone.
ii) Spinal cord.
iii) Insulin.
iv) Thyroxin regulates growth & metabolism in our bodies.
v) Positive geotropism root
Negative geotropism stem.
24.
(a) State & explain fleming’s right hand rule
(3)
b) Any three precautions such as wires used in circuits should be of proper rating
and may be of proper the insulating cover of proper thickness.
Or
a) Yes, magnetic field changes in A. so magnetic flux linked with B changes and
current is induced.
b) i) Right hand thumb rule.
ii) Fleming is left hand rule.
iii) Fleming’s right hand rule.
Section B
25. B
26 A
27. A
28. B
29 A
30 D
31 A
32 B
33 B
Q.34. a) Total R=4+4=8 ohm
V=8volt
I=V/R=8/8
=1A
Potential difference across 4ohm=V’=IR
V’=1*4=4V
b) No,There is no difference in ammeter reading of A1 and A2because both are in
Serie.
35. At constant temperature, current flowing through a conductor is directly
proportional to potential difference. Fig.12.2 of P.No. 204
36. Iron nail turns brown blue colour of CuSo4 changes to greenish blue because of the
formation of ferrous sulphate.
Fe + CuSo4
FeSo4+ Cu
SAMPLE PAPER NO 6 (SA1)
Session 2015-16
Class –X (SCIENCE)
Total Marks : 90
Total Time:3 hrs
General Instructions:
g) All questions are compulsory.
h) The question paper comprises of two sections, A and B. You are to attempt both the sections.
i) Questions 1 to 3 in section A are one mark questions. These are to be answered in one word or
in one sentence.
j) Questions 4 to 6 in section A are two marks questions. These are to be answered in about 30
words each.
k) Questions 7 to 18 in section A are three marks questions. These are to be answered in about 50
words each.
l) Questions 19 to 24 in section A are five marks questions. These are to be answered in about 70
words each.
m) Questions 25 to 27 in section B are 2 marks questions and Questions 28 to 36 are multiple
choice questions based on practical skills. Each question of multiple choice questions is a one
mark question. You are to select one most appropriate response out of the four provided to
you
1]
Name the hormone that controls the rate of respiration. Also name the part of the brain responsible for
controlling respiration. [Marks:1]
2]
Why is it advised not to use copper or brass vessels to store pickles or curd?
[Marks:1]
3]
Which is having more resistance: A 100 W bulb or a 60 W bulb? [Marks:1]
4]
A white powder is added while baking breads and cakes to make them soft and fluffy. What is the name
of the powder? What are the main ingredients in it? What are the functions of each ingredient? [Marks:2]
5]
Write any two causes that may damage the kidney of a person.
[Marks:2]
6]
Explain the significance of peristaltic movement that occurs all along the gut during digestion.
[Marks:2
7]
You are given two solar cookers, one with a plane mirror as reflector and the other with concave mirror
as reflector. Which one is more efficient? Give reason for your answer. State one more use of concave mirror.
[Marks:3]
8]
State the law that relates current through a conductor and the potential difference between its ends.
Represent the law mathematically. Represent graphically, the variation of current I as a function of potential
difference V. [Marks:3]
9]
In the circuit, the two resistance wires A and B are of same length and same material, but A is thicker
than B. Which ammeter A1 or A2 will indicate higher reading for current? Give reason.
[Marks:3]
10]
A student while studying the force experienced by a current carrying conductor in a magnetic field
records the following observations
(a) The force experienced by the conductor increases as the current is increased
(b) The force experienced by the conductor decreases as the strength of the magnetic field is increased.
(c) Which of the two observations is correct and why? What is resistance of a conductor due to? [Marks:3]
11]
A solution of a substance 'X' is used for white washing.
(i) Name the substance 'X' and write its formula.
(ii) Write the reaction of the substance 'X' named in (i) above with water.
(iii) Write the balanced equation for the following chemical reaction:
Barium chloride + Aluminiumsulphate--------->Barium sulphate + Aluminium chloride
[Marks:3]
12]
What is the main ore of mercury? Explain, how mercury is obtained from this ore? Also write the
reaction involved in the extraction
[Marks:3]
13]
(a) Define 'water of crystallisation'.
(b) Give two examples of substances having water of crystallization. Write their chemical formula also.
[Marks:3]
14]
(a)
Using a simple experiment, how can you prove that Magnesium is placed above Zinc in the
reactivity series?
(b)
Why copper metal cannot liberate Hydrogen when reacting with dil. HCl?
[Marks:3]
15]
Draw a diagram of human brain and label any four parts. Write one function each of any two parts.
[Marks:3]
16]
What is chemotropism? Give one example. Name any two plant hormones and mention their functions.
[Marks:3]
17]
Write one feature which is common to each of the following pairs of terms:
(i) Glycogen and starch
(ii) Chlorophyll and haemoglobin
(iii) Arteries and veins
[Marks:3]
18] In a class-room, there were four or five students who were not able to read the material written on black
board. The other students of class helped them to sit at the front seat, so that they can also read the material
written on blackboard What can be the reason behind it, what will you recommend these students and what
precautions you will insist them?
[Marks:3]
19]
Two identical resistors, each of resistance 50 are connected (i) in series (ii) in parallel, in turn; to a
battery of 10 V. Calculate the power consumed in the combination of resistor in the two cases and ratio of the
power consumed in the combination of resistor in the two cases.
[Marks:5]
20]
(a)
Name the process by which sodium hydroxide is prepared from sodium Chloride? Why it is
called so process and write down the balanced chemical equation.
(b)
What will be the pH of the following salts?
(i)
Salt made of strong acid and strong base
(ii) Salt made of strong acid and weak base
21.
(a) A milkman adds a very small amount of baking soda to fresh milk.
(i) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(ii) Why does this milk take a long time to set as curd?
(b) What is a neutralisation reaction? Give two examples.
[Marks:5]
22]
(a)
What are amphoteric oxides? Give two examples.
(b)
Metals such as Sodium and Potassium are kept immersed is Kerosene, why?
(c)
Give the balanced chemical equation for the reaction between Al and steam.
(d)
Name a non metal
(i)
Which is a liquid at room temperature?
(ii) Which is lustrous?
OR
(a) What are the main two allotropes of carbon? Distinguish these two allotropes on the basis of hardness and
electrical conduction.
(b) Why Aluminium articles have a longer life and attractive finish compared to many other metals?
(c) Explain the following terms
(i) Ore
(ii) Gangue
(d) What is common feature in the electronic configuration of metal atom?
[Marks:5]
23]
(a)
Draw diagram of human alimentary canal and label the following
(i)
Part in which starch digestion starts
(ii)
Part in which bile is stored
(iii)
Part in which nutrients are absorbed
(iv)
Part in which water is absorbed
(b)
Mention the role of hydrochloric acid in the stomach.
(c)
What function is served by the following:
(i)
Gastric sphincter
(ii)
Anal sphincter
.
[Marks:5]
24]
Briefly explain an activity to plot the magnetic field lines around a straight current carrying conductor.
Sketch the field pattern for the same, specifying current and field directions.What happens to this field,
(i) If the strength of the current is decreased?
(ii) If the direction of the current is reversed?
Marks:5]
Section- B
25.Two colours seen at the extreme ends of pH chart are
(a) red and blue (b) red and green (c) green and blue (d) orange and black
26. A colourless and odourless gas is liberated when hydrochloric acid is added to a solution of washing
soda. The name of the gas is :
(a) Carbon dioxide. (b) Nitrogen dioxide. (c) Sulphur dioxide. (d) Sulphur trioxide
27. When crystals of FeSO4 are strongly heated the residue obtained is
(a) red in colour. (b) blue in colour. (c) green in colour. (d) colourless.
28. Reddish brown deposit observed on iron nails, when these are kept in aqueos solution of
coppersulphate solution is that of
a) Cu2O b) CuO c) Cu d) CuS
29 Rahul took some zinc granules in a test tube and added dilute HCl to it. He observed that
the colour of the zinc granules changed to
a) Yellow b) brown c) black d) white
30 What is the least count of the following voltmeter ?
a)0.5 V b) 0.1 V c) 0.05 V d) 0.005 V
31. Resistance of a conductor depends on
a) Its length
b) Area of cross section
c) Material of the conductor
d) All the above
32. Four students measured the following readings by observing, the position of pointer of voltmeter
a) 2.5V b) 2.0 V c) 2.2 V d) 2.4 V
33
In the experiment on finding equivalent resistance of two resistors, connected in series, four students I, II, III
and IV set up the circuit as shown below :
The correct connections have been made by student
I b) II c) III d) IV
34. In domestic circuits the colour of neutal wire is :
Black b) red c) green d) orange
Q 35. .What is meant by the term magnetic field lines ? List any two properties of magnetic
field lines? (2 MARK)
Q36. What is an oxidation reaction? Identify in the following reactions
(iii)
(iv)
The substance oxidized
The substance reduced
Zno + C Zn + CO
2 marks
ANSWERS KEY SAMPLE PAPER NO 6 (SA1)
SECTION-A
1] Adrenaline controls the rate of respiration. Pons is the part of the brain which controls the rate of
respiration. 1
2] Acid present in pickles or curd will react with metals like copper and poisonous salts are produced.
1
3] 60 W bulb because ie resistance is inversely proportional to the power.
1
4] When aluminium powder is heated with manganese dioxide the following reaction takes place:
When Mn powder is heated with aluminum dioxide no reaction takes place because Mn is less reactive than Al
and hence there will be no displacement reaction.
2
5]
Baking powder is added to make breads soft and fluffy.
Baking soda and an edible acid like tartaric acid are its main ingredients.
Baking soda (Sodium hydrogen carbonate) is added to release CO2 gas when heated.
Tartaric acid is added to avoid the bitter taste by reacting with the Na2CO3 which isformed by the
heating of NaHCO3.
2
6]
(i) Kidney infection or injury to kidneys.
(ii) Restricted blood flow to kidneys.
2
7]
The lining of canal has muscles that contract rhythmically in order to push the food forward.
Peristaltic movement is necessary to move the food in a regulated manner along the
digestive tube so that the food can be processed properly in each part
3
8]
Solar cooker with concave mirror reflector is more efficient.
Because concave mirror can focus the heat radiations to the material kept inside to increase the
temperature.
Concave mirror is used in headlight of vehicles or as shaving mirror.
3
9]
Ohm's law relates current and potential difference.
According to this law:
V/I = constant = R
3
10]
Ammeter, A1 will show higher reading.
Because, as wire A is thicker than B, A has lesser resistance. So higher current will be drawn by A from
the battery and hence ammeter A1 will show higher reading. 3
11]
Observation a is correct.
Because force experienced by a current carrying conductor in a magnetic field is proportional to the strength of
the current. Resistance of a conductor is due to the obstruction to the flow of electrons due to the collisions
with atoms and other electrons.
12]
(i) The substance 'X' is calcium oxide. Its chemical formula is CaO.
(ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).
iii)write the equation
3
13]
Main ore is cinnarbar, HgS.
When it is heated in air, it is first converted into mercuric oxide (HgO). Mercuric oxide is then reduced to
mercury on further heating.
3
14]
(a)
Water of crystallisation is the number of water molecules that combine chemically in definite molecular
proportion, with the concerned salt in the crystalline state.
(b)
Two correct examples are:
Copper sulphate ,chemical formula = CuSO¬¬4.5H2O
Washing soda, chemical name = Na2CO3.10 H2O.
3
15]
(a) we can show it by an experiment of displacement reaction in which Mg rod is dipped in ZnSO4
solution. Magnesium displaces zinc from zinc sulphate solution.
(b)Cu is less reactive then hydrogen and thus place below hydrogen in the reactive series of metals,
hence cannot displace hydrogen in dilute HCl.
3
16]
(a)
Functions:
(i) Cerebrum:It controls the conscious sensations.
(ii) Mid brain: It controls the auditory impulses. 1+1+1=3
17]
Chemotropism – Movement of plant parts due to chemical stimulus is called chemotropism.
Example
- Growth of pollen tube.
Plant Hormones:
(i) Auxin - It helps the cells to grow longer at shoot tips.
(ii) Gibberellin – Growth of stem.
1+1+1=3
18]
(i) Glycogen and starch – Both are carbohydrates and stored food products.
(ii) Chlorophyll and haemoglobin – Both are pigments.
(iii) Arteries and veins – Both are blood vessels.
1+1+1=3
19]
Myopia (Reason)
Get the proper check up for the eyes.
Should wear spectacles as recommended by doctor.
Associated Value : The learners will be able to handle eye sight disorder if any in their life.
2+3=5
20]
Series:
OR
For maximum resistance, resistors are to be connected in series.
For maximum current, resistance has to be minimum and so resistors are to be connected in parallel.
I series = V/R series
= 6V/9 = 0.67 A
I parallel = V/R parallel = 6V/2 = 3A
Parallel connection is preferred over series for house hold circuits.
2+3=5
21]
(a) Chloralkali process is used to prepare sodium hydroxide using sodium chloride.
When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to
form sodium hydroxide. The process is called the chlor-alkali process because of the products formed– chlor for
chlorine and alkali for sodium hydroxide.
(b)
(i) 7
(ii) less than 7
2+3=5
OR
(a)
(i) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because in
alkaline condition, milk does not set as curd easily.
(ii) Since this milk is slightly basic than usual milk, acids produced to set the curd are
neutralised by the base. Therefore, it takes a longer time for the curd to set.
(b) A reaction in which an acid and base react with each other to give a salt and water is
termed as neutralisation reaction. In this reaction, energy is evolved in the form of heat.
For example:
(i) NaOH + HClNaCl + H2O
(ii) During indigestion (caused due to the production of excess of hydrochloric acid in the
stomach), we administer an antacid (generally milk of magnesia, Mg(OH)2 which is
basic in nature). The antacid neutralizes the excess of acids and thus gives relief from
indigestion. Mg(OH)2 + 2 HCl MgCl2 + 2 H2O
22]
(a)Amphoteric oxides are those oxides which show both acids as well as bases to form salts and water.
Ex: Aluminium metal reacts in this manner with acids and bases.
SnO2 is also an example of amphoteric oxides.
(b)
Metals such as Sodium and Potassium are kept immersed is Kerosene becausethey are very reactive
and have high affinity towards oxygen and will violently react with atmospheric oxygen on contact with air.
(c)
Aluminium reacts readily with steam to give aluminium oxide and hydrogen gas, the reaction does not
always occur. This is due to a thin but strong layer of aluminium oxide being coated onto the metal, thus
preventing it from the reaction. aluminium + steam aluminium oxide + hydrogen 2Al(s) + 3H2O(g) Al2O3(s) +
3H2(g)
[1]
(d)
(i)
Bromine
(ii)
Iodine
2+1+2=5
Or
(a) Diamond and graphite are the two allotropes of carbon.
Diamond –
• hardest substance
• electrical insulator
Graphite –
• comparatively soft, it is slippery over layers
• good electrical conductor
(b) Aluminium articles have a longer life and attractive finish compared to many other metals because of the
formation of a thin transparent protective film cover of Aluminium oxide on the surface of Al formed due to its
spontaneous reaction with oxygen.
(c) (i) Ore : An ore is a type of rock that contains minerals with important elements including metals. The ores
are extracted through mining; these are then refined to extract the valuable element(s).
(ii) Gangue: In mining, gangue is the commercially worthless material that surrounds, or is closely mixed with, a
wanted mineral in an ore deposit.
(d) Electronic configuration of metal atom is significant to know about the kind of bond that the metal will be
forming for example in the formation of calcium chloride, chlorine only needs one electron to complete its
octet so two atoms of chlorine accept one electron each lost by calcium ion.
23]
(i)
(ii)
(iii)
(iv)
(b)
(a)ncert page no 99 fig 6.6
Part in which starch digestion starts – Mouth
Part in which bile is stored – Gall Bladder
Part in which nutrients are absorbed – Small intestine
Part in which water is absorbed – Large intestine
Kills bacteria in the stomach (1/2) provide acidic medium for the action of pepsin.
(c)
(i) Controls the release of food from the stomach to small intestine.
(ii) Controls the release of undigested waste from the rectum through the anus. 1+1+1+1+1=5
OR
24]
Brief explanation of activity:
Connect the circuit as shown in the figure below. Switch on the battery so that the current begins to flow.
Sprinkle some fine iron filings around the current carrying wire. Tap the surface gently. The iron filings get
arranged in concentric circles.
When current is decreased, field gets decrease
When the current is reversed, field also gets reversed
.
2+3=5
Section B
25) b
26) a
27) d
28) c
29) c
30) a
31) d
32) c
33) c
34) Correct Answer
1*9=9
2
35. The field lines which emerges from north and merges at south
1+1/2+1/2
(i) They never intersect each other
(ii) They have maximum strength at poles
36. If substance gains oxygen during the reaction.
1+1/2+1/2
Oxidation C
Reduction ZnO
SAMPLE PAPER NO-7
CLASS- X
Time:3 hrs
SUBJECT-SCIENCE
M.M-90
General Instructions:
n) All questions are compulsory.
o) The question paper comprises of two sections, A and B. You are to attempt both the
sections.
p) Questions 1 to 3 in section A are one mark questions. These are to be answered in one word
or in one sentence.
q) Questions 4 to 6 in section A are two marks questions. These are to be answered in about 30
words each.
r) Questions 7 to 18 in section A are three marks questions. These are to be answered in about
50 words each.
s) Questions 19 to 24 in section A are five marks questions. These are to be answered in about
70 words each.
Questions 25 to 27 in section B are 2 marks questions and Questions 28 to 36 are multiple choice
questions based on practical skills. Each question of multiple choice questions is a one mark
question. You are to select one most appropriate response out of the four provided to you
SECTION-A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Give an example of decomposition reaction carried out with the help of electricity.
Name one gland in human body which secretes digestive enzymes as well as hormone.
State the physical quantity which is equal to the ratio of potential difference and current.
An electric bulb is connected to a 220V generator. The current is 0.50 A. What is the power of the
bulb?
Draw the electron dot diagram of a hydrogen chloride molecule?
Why do acids not show acidic behaviour in the absence of water?
What are auxins? Where are they synthesised in the plant body define its function?
AB is a thick copper wire. When electric current ‘I’ flows through the wire, what change is observed
in the compass needle placed near the wire? Give reason for this observation. State the change that
would be observed if the direction of the electric in the wire is reversed.
Draw the magnetic field lines(including field directions) of the magnetic field due to a long straight
solenoid . What important property of this field is indicated by this field line pattern?
What are nastic and curvature movements? Give example of each.
Write the difference between cerebellum and cerebrum.
State the chemical name of Plaster of Paris. Write a chemical equation to show the reaction
between Plaster of Paris and water.
A milkman adds a very small amount of baking soda to fresh milk. Why does he shift the pH of fresh
milk from 6 to slightly alkaline? Why does this milk take a long time to set as curd?
What is an electromagnet? List any of its two uses.
Demonstrate the reaction between zinc granules and dil. Acid. Write the balanced chemical
equation for the reaction.
(a) What happens at the synapse between two neurons?
(b) What is the function of receptors in our body?
17. Raunak is fond of pickle which are prepared from vinegar or mustard oil . It contains lot of spices and
common salt. It may cause hyperacidity and indigestion. The intake of excess of common salt may result in
high blood pressure. It is harmful for health. Amit does not take pickles.
(a) Which acid is present in vinegar?
(b) Why should we take less common salt?
(c) Which one is better, oil or vinegar for pickles?
18. For the circuit shown in the diagram given below :
(a) the value of current through each resistor
(b) the total current in the circuit
(c) the total effective resistance of the circuit.
19. (a) Give an example of of a metal which
(i) can be easily cut with a knife..
(ii) is liquid at a room temperature.
(b) Write chemical equation for the reaction when ?
(i) steams acts on red hot iron. (ii) Zinc is added to iron(II) sulphate solution..
(c) What are alloys?
(d) Why are food can coated with tin and not zinc?
20 (a) Why does an aqueous solution of an acid conduct electricity?
(b) How does the concentration of hydronium ions(H3O+) change when a solution of acid is diluted?
(c) Which has higher pH value,aconcentrted or dilute solution of hydrochloric acid?
(d) What do observe on adding dilute hyhrchloric acid to
(i) Sodium carbonate placed in test tube.
(ii) Zinc metal in a test tube?
21. (a) Draw a sectional view of a human heart and label on it aorta ,pulmonary vein, vena cava ,left
ventricle..
(b) Why double circulation of blood necessary in human being?
22. (a) Draw a schematic diagram showing common domestic circuit.
(b) State the function of earth wire. Why is it necessary to earth metallic appliances such as electric
iron?
23. (a) A coil of insulated copper wire is connected to a galvanometer. What will happen if bar magnet is
(i) pushed into the coil with its north pole entering first?
(ii) withdrawn from inside the coil?
(iii) held stationary inside the coil?
(b) Name the above phenomenon and mention the name of the scientist who discovered it. State the
law that relates the direction of current in the coil with the direction of motion of the magnet.
24. What is phototropism and geotropism? With labelled diagrams, describe an activity to show that light
and gravity change the direction that plant parts grow in it.
SECTION-B
25. In the experimenton on finding the equivalent resistance of two resistors,connected in parallel,the
voltmeter has been corredtly connected in:
(a) Circuit I only (b) circuit II only (c) both circuits I and III (d) both circuits II and IV
26. A student sets ups an electrical circuit for the verification of o
ohms law .He observes that voltmeter reading gets in reverse direction ..The student should:
(a) get the voltmeter replaced .
(b)decrease resistance with the help of rheostat.
(c)connect voltmeter in series.
27. A student performs an experiment to find the equivalent resistance of two given resistors R1 and R2
first , when they are connected in series and next , when they are connected in parallel .The two values of
the equivalent resistance obtained by him are Rs and Rp respectively, He would find that :
(a) RS<RP (b) RS>RP (c) RS =RP= (R1+R2)/2 (d) RS=RP but not equal to(R1+R2)/2
28. On adding a few drops o universal indicator to three unknown colourless solution P,Q,and R taken
respectively in the three test tubes shown in following diagrams ,a student tobserved the changes in colour
as green in P ,red in Q ,and violet in R.
The decrease order of pH of solution taken is:
(a)
(b)
(c)
(d)
P>Q>R
R>P>Q
Q>P>R
R>Q>P
29. A dilute solution of sodium carbonate was added to test tube –one containing dil.HCL(A) and other
solution containgdil.NaOH (B)
The correct observation was:
(a) A brown –coloured gas liberated in test tube A.
(b) A brown –coloured gas liberated in test tube B.
(c) A colourless gas liberated in test tube A
A colourless gas liberated in test tube B.
30. On reactingwithdil.HCL acid which one of the following gives a colourless gas which when passed
through lime water turns it milky.
(a) zinc metal
(b) sodium hydroxide
(c) sodium carbonate
(d) ethanoic acid
31 Sequence in preparing a temporary mount is
(a) Stainig, mounting, putting coverslip
(b) Staining , puttimg coverslip, mounting
(c) Putting coverslip, staining , mounting
(d) Mounting , staining , putting cover slip
32. The figure given below illustrate boiling of leafs to remove chlorophyll. This is one of the steps in the
experiment to show that light is necessary for photosynthesis
The correct method is
(a) I
(B) II
(c) III
(d) IV
33. An apparatus is set up to show that germinating seeds release carbon dioxide during respiration.
Which observation out of the following should be made to get correct results
(a) carefully observe if there is any change in the size of germinating seeds.
(b) see if the KOH in the test tube has absorbed the CO2 released by the germinating seeds
(c) check the change in the level of water present in the beaker or bent tube
(d) check if CO2 is coming into the delivery tube
34. What precautions would you take while handling Quicklime?
35. State one advantage and one disadvantage of series circuit.
36. Differentiate between aerobic and anaerobic respiration.
ANSWERS KEY
SECTION-A
1.Water
2.Pancreas
3. resistance
4. P= VI = 220x 0.5 = 110W (1/2+1+1/2)
5. Correct diagram
6 Due to absence of Hydrogen ions.
7 Plant hormone .present in growing tips promotes growth.
8. deflection in magnetic needle
A current carrying wire creates magnetic field around it.
9. For diagram refer to ncert text book
Property : magnetic field lines inside the solenoid are parallel straight lines close to each other indicate
the strength of magnetic field is same at all points .
10. Correct explanation with example (1.5x 2)
11.Any two differences (1.5 x 2)
12. CaSO4 . ½ H2O
Correct equation. (1+2)
13. To keep the milk fresh for long time
Because medium is alkaline and curd is acidic.
14. Correct definition any two uses.
15. proper diagram of this activity refer to ncert text book
Correct equation.
16.(i) the two neurons join together to transform message from one neuron to other.
(ii) Correct explanation. It detect all information from environment and feed to the nervous system.
17. (a) Acetic acid
(b) increases bloodpressure and other heart ailments
(c) Vinegar better as oil has fats and high calorific value and increase weight.
18. Data
R1 = 5ohm
V= 6V
R2 = 10 ohm I= ?through each resistor
R3 = 30 ohm I= ? total
R total = ?
(a) I5ohm = V/R1=6/5=1.2A
I10ohm=V/R2=6/10=0.6A
I30ohm=V/R3=6/30=0.3A
(b) Total current I=I5ohm +I10ohm+I30ohm
I=1.2+0.6+0.2 = 2.0 A
(c)1/RP=1/R1+1/R2+1/R3(PARALLEL)
=1/5+1/10+1/30=6+3+1/20=10/30=1/3
RP=3ohm
19. (i) Sodium (ii) Mercury
b) (i) 3 Fe(s) + 4H2O(g)  Fe2O3 + 4H2(g)
(ii) Ze(s) + FeSO4(aq)  ZnSO4(aq) + Fe(s)
(c) Alloys are homogeneous mixture of two or more than two metals and metals and non-metals.
(d) Food cans are coated with tin and not zinc because tin is less reactive than zinc and does not corrode
easily and it is cheaper
20. (a) Aqueous solution of acid releases ions so that it can conduct electricity.
(b) When solution of an acid is diluted , concentration of hydronium ions (H3O+) decreases.
(c) Dilute solution of HCL will have higher pH than conc. Solution
(d) (i) Na2CO3 + 2HCl(dil)  2NaCl + CO2 + H2O
effervescence of CO2 gas is seen
(ii) Zn(s) + 2HCl(dil) ZnCl2 + h2(g)
odourless and colourless gas hydrogen is evolved with bubbles on surface oz zinc
21.
(d) (b) The blood passes through the heart twice. Right side of the heart receives deoxygenated blood
which is circulated to lungs for purification. At the same time the left side of the heart receives
oxygenated blood which is circulated to the body. This is called double circulation.
22. Refer to ncert text book
(b) provides low resistance conducting path for passage of current.It keeps the potentialof the
metallic body at zero.
23. (a) The magnetic linked with coil increases/changes It causes electric current to induce in it.
(b) Magnetic field lines in the coil changes in decreasing order. The direction of induced current is opposite
to induced current in case a.
(c) -No deflection.
24. Phototropism:
The movement of plant towads the light is called phototropism
Occurrence:
The plant at its root tip consists of auxin which helps in the growth of a plant and the plant moves towards
the light.
Activity
Take a few seeds which are germinating and place it on the mesh on conical flask which contains water.
After a few days the seeds, roots will move towards the water and shoot moves towards the light
SECTION B
25(c)
26 (c)
29(c)
30 (b)
34 (i) causes severe burns handled with spatula
27(b)
31 (a)
(ii) reaction is exothermic . Water poured over Quicklime slowly.
35. Advantage (i) Batteries connected in series to get high voltage
Disadvantage If one component fails the total circuit is broken.
32(c)
28(b)
33(b)
36. Any two differences.
Important Formula
Chemical reactions and equations
1.𝑍𝑛 + 𝐻2 𝑆𝑂4
𝑍𝑛𝑆𝑂4+ 𝐻2
2. 2𝑀𝑔 + 𝑂2
2 𝑀𝑔𝑂
Combination Reaction
1. H + O2
2. CaO + H2O
H2O
Ca(OH)2
Decomposition Reaction
1. FeSO4
Heat
2. Pb(NO3)2
Heat
Fe2O3 +SO2 + SO3
2PbO + 4NO2 +O2
Displacement Reaction
1. Zn + CuSO4
2. Pb + CuCl2
ZnSO4 + Cu
PbCl2 + Cu
Double Displacement Reactions
1. Na2SO4 + BaCl2
2. ZnCl2 + H2SO4
BaSO4 + 2NaCl
ZnSO4 + 2HCl
Oxidation Reduction Reactions
1. 2Cu + 2H2O
2CuO + 2H2
Copper is Oxidised to Copperoxide
Water is reduced to hydrogen gas
(ACIDS BASES AND SALTS)
Acid + Metal
Salt + Hydrogen Gas
1. 2HCl + Zn
ZnCl2 + H2
2. 2HNO3 + Zn
3)2 + H2
3. H2SO4 + Zn
ZnSO4 + H2
Base + Metal
Salt + Hydrogen
1. 2NaOH + Zn
Na2ZnO2 + H2
2. 2NaOH + 2 Al +2H2O
2 NaAlO2 + 3H2
Action of Acids with metal Carbonates and metal bicarbonates
1. Metal Carbonate + Acid
Salt + Carbondioxide + Water
Na2CO3(s) + 2HCl(aq)
aq) + H2O(l) + CO2(g)
2. Metal bicarbonate + Acid
Salt + Carbondioxide + Water
NaHCO3 + HCl
NaCl + CO2 + H2O
Acids give H3O+ And Bases Give OH- Ions in water.
Hcl + H2O
H3O + Cl
+
KOH
K + OHLime water Test : On passing the CO2 gas evolved through lime water,
Ca(OH)2 (aq) + CO2(g)
3(s) + H2O(l)
Lime water
White precipitate
On passing excess CO2 the following reaction takes place
CaCO3(s) + H2O(l) + CO2(g)
Ca(HCO3)2 aq
Soluble in water
Neutralisation Reactions
Base + Acid
Salt + Water
NaOH(aq) + HCl(aq)
NaCl(aq) + H2O(l)
Neutralisation reacton takes place when the effect of a base is nullified by
an acid and vice versa to give salt and water.
Reactions of metal oxides with acids
Metal Oxide + Acid
CuO + HCl
CuCl2 + H2O
Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base
Ca(OH)2 + CO2
CaCO3 + H2O
2NaCl(aq) + 2H2O(l)
2NaOH(aq) + Cl2(g) + H2(g)
Bleaching Power
Preparation :+
Cl2
CaOCl2 + H2O
2
calcium hydroxide chlorine
bleaching water
Baking Soda
Common name – Sodium Hydrogen Carbonate
Preparation :- NaCl + H2O + CO2 + NH3
NH4Cl + NaHCO3
On heating NaHCO3 produces :
NaHCO3
Na2CO3 + H2O + CO2
Washing Soda
Preparation :- Recrystallisation of sodium carbonate
Na2CO3 + 10H2O
Na2CO3. 10H2O
Plaster of Paris–PREPARATION.
. ½ H2O + 1 ½ H2O
CaSO4 .2 H2O
Plaster of paris
Gypsum
IMPORTANT FORMULAE OF METALS AND NON METALS
Chemical properties of metal
(9) Reaction with air: - Metal + Oxygen
Metal Oxide
4Na + O2
(10)
2 Na2O
Reaction with water: - Metal + Water
Metal Oxide + Water
2K + 2 H2O
Metal Oxide + Hydrogen
Metal Hydroxide
2KOH + H2
(11)
Reaction with Acid: - Metal + Acid
Salt + Hydrogen
2Na + 2HCL
2NaCl + H2
(12)
Reaction with salt: - More reactive metal displace less reactive method from their salt
solution.
Example: - Zn + CuSO4 →
ZnSO4 + Cu
The arrangement of metals in the order of their decreasing reactivity is known as activity
series.
K
Most Reactive Metal
Na
Ca
Mg
Al
Zn
Fe
Reactivity Decreases
Pb
H
Cu
Hg
Ag
Au
Least Reactive Metal
Extracting Metals low in the activity series: 2HgS + 3O2
2HgO
2HgO + 2SO2
2Hg + O2
Extracting metal in the middle of the activity series: Roasting: - 2ZnS + 3 O2
2ZnO + 2SO2
Calcination: - ZnCO3
ZnO
ZnO + CO2
+C
Zn + Co
Thermit Reaction
Fe2O3 + 2Al
2Fe +Al2O3 + Heat
Extracting metals towards the top of the activity series: At Cathode
Na⁺
+ e⁻
At Anode
2Cl⁻
→
→
Na
Cl2 + 2e⁻
CORROSION: - Combining of metal with oxygen in air in presence of moisture is known
as corrosion.
PERIODIC CLASSIFICATION OF ELEMENTS
At present there are ,118 elements are known to us .All these have different properties.Out of these
118,only 98 are naturally occurring .
EARLY ATTEMPTS AT THE CLASSIFICATION OF ELEMENTS
1.Dobereiner’straids
According to dobereiner, when the three elements in a traid were written in order of increasing
atomic masses,the atomic mass of the middle element was roughly average of the atomic masses of
the other two elements.
Limitations :
1This system was not found to be useful.
2.He could identify only three traids at that time.
2.Newland’s law of ocatves
According to Newland,When the elements are arranged in order of increasing atomic masses then
every eighth element had properties similar to that of the first .It is also called the”Law of Ocatves”.
Limitations:
1.It was applicable only up to calcium.
2,. He assumed only 56 elements in nature.
3.He adjusted two elements in the same slot.
3.Mendeleev’s periodic table
It states that ‘The properties of elements are the periodic function of their atomic masses’.
Limitations
1.No fixed position was given to Hydrogen.
2. Atomic masses were not increasing in regular manner.
THE MODERN PERIODIC TABLE
According to modern periodic table ‘Properties of elements are a periodic function of their atomic
number.’
POSITION OF ELEMENTS IN THE MODERN PERIODIC TABLE
The modern periodic table has:
18 vertical columns
are called GROUPS
7 Horizontal rows
are called PERIODS.
Valency of elements in a group is
same.
GROUP
Be (4) 2 ,2
Mg(12) 2 ,8 ,2
Ca(20) 2 ,8 , 8, 2
Valency increases from 1 to 4 and decreases to 0.
Li
Be
B C
N
O F
Ne
3
4
5 6
7
8
9
10
2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8
The
nu
mb
er
of
elements in a period is based on how electrons are filled into various shells.( 2n2)
For example;
K shell---2 x 1)2 = 2,hence the first period has 2 elements.
L shell—2 x (2)2 = 8, hence the second period has 8 elements.
M shell---2 x (3)2 = 18,but the outermostshell can have only 8electrons,so the third period has only 8
elements.
TRENDS IN THE MODERN PERIODIC TABLE
VALENCY
Electrons present in the outermost shell or valence shell are called valence electrons.
Atomic radius
Atomic radius is the distance between the centre of the nucleus and the outermost shell of an atom.
It decreases along the period and it increases along the group.
IONIZATION ENERGY
It increases along the period and decreases along the group.
Metallic character (Electropositivity)
It decreases along the period and increases along the group.
NonMetallic character(Electronegativity)
It increases decreases along the period and decreases along the group.
Elements have same valence
electrons.
GROUP 1
H (1) 1
Li(3) 2 1
Na(11)2 8 1
K( 19) 2 8 8 1
Valence electrons increases as atomic number
Increases.
PERIOD2;
Li
Be
B C
N
O F
Ne
3
4
5 6
7
8
9
10
2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8