Download 10th-chem - Uday Pre

UNIT-1
I.
ENVIRONMENTAL ISSUES
Choose the correct answer.
1.Identify from the following a biodegradable pollutant
a. Sulphur compounds
b. sewage water
c. lead compounds
d. pesticides
2.Which of the following is the most hazardous air pollutant?
a.Oxides of nitrogen
b.Carbon dioxide
c.Carbon monoxide
d.oxides of sulphur
3.Agricultural wastes are causing
a.Water pollution
b.both water and land pollution
c.air pollution
d.land pollution
4.Acid rain refers to precipitation with a pH of
a.less than 5.6
b.between 5.6 and 5.8
c.about 7.0
c.above 7.0
5.Which chemical substance is responsible for breaking down ozone
a.Mercury
b.Carbon
c.Lead
d.Chlorine
6.Globle warming can be reduced by minimizing the release of
a.Chlorofluorocarbons
b.sewage water
c.green house gases
d.Agriculuture waste
II.Fill in the blanks.
1.Waste incineration releases mainly carbon monodioxid.
2.detergents cause a decrease in the content of water oxygen.
3.Ozone in the atmosphere protects us from harmful ultra violet
radiation.
4.Oxides of nitrogen and sulphur are mainly responsible for causing
health effects.
5.Noise beyond 100 db is dangerous to human ear.
III.Answer the following.
1.Distinguish between degradable and non degradable pollutants.
Give examples.
Ans: * Those pollutants that can degraded by biological activity or by
any means are called biodegraded pollutants.Eg:-Sulphur
dioxide,Carbon dioxide,Sewage product etc.
 The pollutants that cannot be degraded by any means are called
non biodegradable pollutants. Eg:-lead vapour from
petrol,detergent,DDT,insecticides etc.
2.List out main sources of air pollution.
Ans:-The main sources of air pollution are
a.Coal combustion
b.diesel combustion
c.petrol combustion
d.Smoking of tobacco
e.Waste incineration
3.Write a brief note on marine pollution.
Ans:-Most of the pollutant reaching the atmosphere condense and
fall into oceans .Agricultural run off.Inustrial effluents,oil seepage
from huge tankers are causing marine pollution.Every year about
60,000 barrels of oil is entering the sea.
4.Explain the need for treating sewage water.
Ans:- Sewage water is use source of disease producing micro
organisms.The nitrates and phosphate present in it may lead to
eutophication.So we need to treat it before letting out into the
ocean.
5.List the effects of noise pollution.
Ans:-Noise pollution directly effects the human nervous system
.causing deafness,headache,high blood pressure and heart related
disorders. Harsh noise causes uneasiness and behavioural
discomfort.Noise pollution affect animal very seriously.
6.Write a brief note on radiation pollution.
Ans:-Three main radiations of radioactive element are Alpha
particles ,Beta particles and gamma particles .The pollution caused
is radioactive pollution .There are other types of radioactive
pollution .They are:a. Nuclear power plants.
b. Nuclear weapons ,disposal of nuclear wastes.
c.Preparation of radioactive isotopes mining and refining of
radioactive substance like uranium.
7.Briefly explain the natural green house effect on earth.
Ans:-Green house effect is a process by which thermal radiation is
absorbed by atmospheric gases and is radiated in all directions.
Earth’s natural green house effect is responsible for sustaining life on
earth. Natural green house effect is helpful in horticulture to provide
warmer temperatures for growing ornamental plants.
8.Suggest measures to control acid rain.
Ans:-Some precautions are to be taken to minimise the production
of sulphur dioxide, nitrogen oxides,carbon dioxide,carbon monoxide
etc in different industries.Controlling of these gases will reduse the
acidic quality of the rain.All the vehicles should maintain their
engine condition in good from so that minimum carbon monoxide
and carbon dioxides are liberated.
UNIT-2
I.
PERIODIC CLASSIFICATION OF ELEMENTS
Choose the correct answer.
1.In a triad of ‘A’,’B’,’C’ elements if the atomic mass of ‘B’ and ‘C ’are
150 and 200 respectively ,the atomic mass of ‘A’ is _100_
a.100
b.125
c.250
d.350
2. In the periodic law the following repeat at regular intervals
general properties.
a. Atomic number
b. General properties
c. Atomic mass
c. Isotopes
3.In the periodic table the elements of 18th group in general do not
form bond.
a.Form ionic bond
b.Form covalent bond
c.Form hydrogen bond
d.do not form bond
4.The following is an example for transitional element uranum.
a. Sodium
b .Chlorine
c. Orgon
d. uranum.
II. Fill in the blanks.
1.The group number of the element neon is 18 .
2.The periodic number of the element aluminium is 3.
3.Horizontal similarity can be observed in the period number 6th to
7th.
4.The first element of 14thgroup is carbon which is a non metal .The
metallic members of this group are Ge,Sn,Pb.
III.Give reasons for the following:
1.’f’block element are kept separately in the periodic table .
Ans: ‘f’ block elements do not fit into the elements of main table as
there is more horizontal similarity rather than verticle similarity in
these elements.
2.Atomic size decreases across the period.
Ans:Across the period there will not be any change in the number of
shells but more electrons are added to the same shell and the
nucleus exerts greater inward pull on the electrons.
3.In the first period hydrogen and helium are not placed adjacent to
each other.
Ans:-Actually helium belongs to 1st period according to its shell
(1s2)but this shell is a completed shell and belongs to 18th group
along with other with other completed shell gases .Therefore helium
is not placed adjacent to hydrogen.
4.In the construction of periodic table the periodic law is broken in
some places.
Ans: Periodic table is constructed for our convenience. But in few
places few elements do not follow the modern periodic law strictly
.Hence to group the elements of similar properties in same group
the periodic law is broken in some places.
IV.Anwer the following :
1.What are periods and groups in the periodic table ?
Ans:- The horizontal rows of elements arranged in a periodic table
are known as periods.
The vertical arrangement of elements arranged in the periodic table
are known as groups. There are seven periods and eighteen table.
2.State the modern periodic law.
Ans:- The periodic table formed on the basis of electronic
configuration of elements is called the modern periodic law . This is
long form of the periodic table.
3.Atomic mass is not useful to construct the periodic table . Give
reasons with an example.
Ans:-* The properties of elements depend upon the number of
electrons present in the valence shell which are related to atomic
number . On other hand atomic mass can in no way determine the
chemical properties.
 If atomic mass is used to construct periodic table ,Isotopes of
some elements cannot not be arranged.
4.In which part of the periodic table do we find mostly non metals ?
Ans:-From 1 to 6 periods and 13th to 18th group we find non metals .
Altogether there are 22 non metals (11 gases 10 solid and 1 liquid).
5.What are transitional elements?
Ans:- Element where electrons of their atoms occupy ultimate shells
leaving penultimate shells partially vacant are called transitional
elements.
6. What are metalloids? Give an example.
Ans:-Element which are not distinctively metals and posses some
physical properties of non metals are called metalloids .Eg:Germanium.
SILICON
I.Choose the correct answer.
1.The acid used to remove untreated silica in extraction of silicon is
Hydrofloric acid.
a.hydrochloric acid.
b.hydrofluoric acid
c.nitric acid.
c.sulphuric acid
2.The other product in the following chemical equation is Si+ 2H2O----SiO2+H2
a.H2
b.O2
c.Si2 d.O3
3.Which silicon compound among these is used as insulating
material?
a. silicon dioxide
b.silicon carbide
c.silicones
d.zeolites
II.Fill in the blanks
1.Two allotropic forms of silicon are amorphous and crystalline.
2.Crystalline silicon is obtained by reducing silicon with coke.
3.When a mixture of silicon and coke is heated in an electric furnace
the product obtained is silicon carbide.
III.Match the following.
1.Water softeners= permutit
2.Abrasive materials = Carborandum
3.Constituent of concrete mixture = silica
IV.Answer the following.
1.What is the role of hydrochloric acid and hydrofluoric acid in the
extraction of silicon?
Ans:- Hydrochloric acid dissolves excess of magnesium oxide in the
extraction of silicon from silicon dioxide. Hydrofluric acid removes
unchanged silica.
2.Name the element which is most abundant in earth’s crust
Ans:-Oxygen is the most abundant element in earth’s crust.
3.Write the chemical equations of the reaction taking place when
silicon reacts with a)Oxygen b) steam
Ans:-a)Oxygen reacting with silicon
Si+O2-----SiO2
b)Steam reacting with silicon
Si+2H2O(steam)---------SiO2+2H2
4.How is silicon carbide obtained?
Ans:-When a mixture of silicon and coke is heated in an electric
furnace , silicon carbide is formed.
Si +C-----SiC
5.Describe the methods of amorphous silicon and crystalline silicon.
Ans:- Extraction of amorphous (powdered) form silicon.
*Finely powdered silica (sand or quartz) is mixed with magnesium
powder and heated in a fire-clay crucible. Magnesium oxide and
silicon are formed.The product is washed with dilute hydrochloric
acid to dissolve magnesium oxides.Then it is washed with
hydrofluoric acid to remove untreated silica. The powder left behind
is silicon in its amorphous form.
SiO2+2Mg------------Si+2MgO
Extraction of Crystalline silicon:
*Crystalline silicon is obtained by reducing silicon with coke. When
excess of silicon is heated with coke in the electric furnace in the
absence of air dark grey coloured silicon is obtained in its crystalline
form.
SiO2+2C-------------Si+2CO
NUCLEAR ENERGY
I.Choose the correct answer.
1.Which of the following source of energy is not considered the
transformation of solar energy ?
a. energy of food
b. energy of petroleum
c. energy of coal
d. energy of fission
2.Which of the following is a nuclear reaction ?
a.Two hydrogen atoms combine to form hydrogen molecule.
b. Sodium atom gives up an electron to become sodium ion.
c. Water splits up into hydrogen and oxygen by electrolysis.
d. Isotopes of hydrogen nuclei combine to form helium nuclei.
3.The equation E=mc2 was theoretical .It received experimental
proof from.
a. nuclear reactions carried out in the laboratory.
b. measurement of molecular mass of a compound formed by
chemical combination.
c. measurement of molecular mass of products of decomposition.
d. The phenomenon of radioactivity.
4.Transmutation means,
a. conversion of mass number of an atom
b. conversion of charge number of an atom
c. mass and energy are inter convertible
d. creation of neutrons by fission
5. Nuclear power reactor is based on the principle of ,
a. exothermic chemical reactions
b. endothermic chemical reactions
c. controlled nuclear fission
d. thermonuclear fusion
6. The nuclear fission chain reaction is initiated by the particle
A. proton
b. neutron
c. electron d. positron
II. Fill in the blanks:
1.Fissionable isotopes of uranium is 92U235.
2.Increasing the percentage of fissionable isotope of uranium in the
natural uranium is called enrichment of uranium.
3.The most dangerous radiation released by radioactive materials is
gamma rays.
4.The equation E=mc2 is derived by the scientist Albert Einstein.
5.The nuclear reaction that cannot be controlled at present is
nuclear fusion.
III. Match the following.
1.92U235
= Nuclear fuel.
2. Graphite =Moderator
3.Control rod =Cadmium
4.Radiation shield = Lead and concrete.
IV Answer the following:
1.Draw a neat diagram of nuclear power reactor and label the parts.
Ans:-Refer page no-127 & Fig-10.2.
2.Draw the schematic diagram of fission chain reaction of 92U235
isotopes.
Ans:- Refer page no-125 & Fig-10.1
3. State any two places in India where the nuclear reactions are
functioning.
Ans: Two of the nuclear reactor are Kalpakam in Tamilnadu ,Kaiga in
Karnataka, (Another nuclear plant at kundankulam is commission in
kundankulam, Trirunelveli district in Tamilnadu).
4.State the precautions to be taken, while handling nuclear reaction
materials.
Ans:- Radioactive materials are hazardous to human health, because
the materials left behind in the nuclear reactor is radio active.
1. The workers, who handle nuclear reactive materials, should wear
lead jackets.
2. Nuclear reactive materials should be kept in glass slabs and
disposed in the deep sea in strong steel containers.
3. Nuclear reactors should be built for away from natural resources
and human beings.
5.How should the spent fuel of a nuclear reactor be disposed?
Ans:- The spent fuel of a nuclear reactor should be kept in glass slabs
and disposed in the deep sea in strong steel container.
6. Explain nuclear fission with an example.
Ans:- According to Albert Einstein’s theory. E =mc2,a certain mass
can be converted into energy . Amount of energy released can be
calculated taking a certain mass.Let us take one a.m.u of mass gets
into energy .1 a.m. u =1.66x10-27Kg.
E =mc2, where E= energy ,m = mass and C=velocity of light.
W= !.66x!0-27x3x108x3x108
= 14.98x1011Jouls.
The energy released is expressed in electron volt (e.v) or million
electron volt (Mev)
1Mev = 1.7x10-13Jouls
Therefore energy released by 1 a. m.u of nuclear mass.
E= 14.98x10-11 /16x10-13
=933.75Mev.
7.Explain nuclear fusion with an equation.
Ans:- Under specific conditions :
*Nuclei of light elements can combine to form a nucleus of high
atomic number.
Eg:-1H2+1H2--------2He4 +energy.
This equation explains two isotopes of hydrogen that is deuterium
nuclei combines to form helium nucleus and energy.
8. State any two differences between chemical reactions and nuclear
reactions.
Ans:- *Chemical reactions
1. Nuclear of an atom does not undergo any change.
2. Mass is conserved.
*Nuclear reactions
1.Nucleus of the atom undergo change.
2.A small amount of mass is converted into energy.