Download Science HW- Class 7

KV CRPF AVADI CHENNAI 65
SCIENCE CLASS 7 HOLIDAY HOME WORK
24-12-2015
I.
Fill up :-
1.
Souring of milk is a _______________ change
Ans :- Chemical
2.
When carbondioxide is passed through line water it turns milky due to the
formation of _________________.
Ans :- Calcium Carbonate
3.
Changes in which new substances are formed are called _____________
change.
Ans :- Chemical
4.
The chemical name of baking soda is __________________
Ans :- Sodium hydrogen carbonate.
25-12-2015
II.
Choose the correct answer :-
1.
Which of the following is not a chemical change
a) burning of coal
b) digestion of food
c) melting of ice
d) rusting of iron
Ans :- Melting of ice.
2.
Anaerobic bacteria digest animal waste and produce biogas (change - A).
The biogas is then burnt as fuel (change - B). The following statement
pertain to these changes choose the correct one.
a) Process - A is a chemical change
b) Process - B is a chemical change
c) Both process A and B are chemical changes
d) Non of these processes is a chemical change
Ans :- Both process A and B are chemical changes
3.
The layer of rust is actually deposit of
a) Iron (III) oxide
b) Mud
c) Water
d) oxygen
Ans :- Iron (III) oxide
4.
The process of depositing a layer of zinc on iron is called.
a) crystallisation
b) galvanisation
c) rusting
d) melting
Ans :- Galvanisation.
26-12-2015
III.
Question and answer :-
1.
Explain why rusting of iron object is faster in coastal areas than in desert.
And :- Coastal areas contains many salts. The salt water makes rust
formation faster.
2.
How would you show that setting of curd is a chemical change?
Ans :- Conversion of milk into curd is a permanent and irreversible lead
to produce new substance with different composition and properties.
27-12-2015
IV.
Fill in the blanks :-
1.
In addition to the rock particles the soil contain _____________
Ans:- Mineral, organic matter, air and water.
2.
The water holding capacity is the highest in _____
Ans:- loamy soil
3.
Clayey and loamy soil are suitable for cereals like ______________
Ans :- Wheat and grams
4.
Each layer of soil is called a ____________
Ans :- horizon
5.
The mixture of rock particles and humus is called _________
Ans :- Soil
28-12-2015
V.
Answer the following :-
1.
List two difference between clayey soil sandy soil.
Ans :Clayey Soil
1. It has good water holding
- It
Sandy Soil
has poor water
holding
capacity
2. It has less percolation rate of
water
2.
capacity
- It has more percolation rate of
water
Explain how soil pollution could be prerented.
Ans :Prerention of soil pollution
3.
1.
Recycle waste
2.
Dispose off sewage property
3.
Use organic manure
What is humus?
Ans :- Dark colored partially decayed organic matter rich in nutrient. It
makes soil porous.
4.
Explain how soil is formed.
Ans :- Big and heavy rocke broken into smaller pieces by action of wind
and climate
-
Small particles get decomposed on exposure to air.
-
Decomposed Vegetable and animals mix with soil
29-12-2015
VI.
Fill int the blanks :-
1.
In cockroaches, air enters the body through ____________
Ans :- Spiracles.
2.
What are stomata?
Ans : - Stomata are tiny pores presention the surface of leaf.
3.
During heavy exercise, leg gets cramp due to ________
Ans :- Lactic acid
4.
What is aerobic Respiration?
Ans :- Repiration occurs in the presence of oxygen
-
harge amount of energy is released
-
Food molecules are brokendown into water and carbondioxide.
30-12-15
1.
Name the organs of breathing in fish.
Ans:- Gills.
2.
What is anaerobic respiration.
Ans:- It occurs in the absence of oxygen
-
Small amount of energy is released.
-
Food molecular are broken down into ethyl alcohol and
carbondioxide
31-12-15
1.
Why do we offers sneez when we inhale a lot of dust - laden air?
Ans :- We sneez to get rid of anwanted particles lid dust from our body. It
allows only clean and dust free air
2.
Name the skeletal structure surrounding the chest cavity.
Ans :- Rib cage.
1-1-16
1.
Name the muscular floor of the chest cavity.
Ans :- Diaphragm
2.
Which procen of respiration releases more energy.
Ans :- Aerobic respiration
2-1-16
1.
Write the similarities between aerobic and anaerobic respiration?
Ans :- Both aerobic and anaerobic respiration produce energy and give
out cabondioxide.
2.
Which of the follosing does not have lungs for breathing ?
(a) lizard
(b) froq
Ans :- Fish
END
(c) fish
(d) fox