Chhattisgarh State Class 7 Science Chapter 2 Solution

CG SCERT Chhattisgarh State Board Class 7 Science (Science and Technology) Chapter 2 Water Exercises Questions and Answers.

(1) a) Ice floats on the surface of water because – (iii) density of ice is less than water.

b) Ratio of hydrogen and oxygen in water is 2:1 – (ii) as per volume

c) Water cycle is a — (i) process of evaporation

d) Distilled water is the closest to — (ii) rain water

(2) Fill in the blanks Answer:

a) Universal

b) Carbon die Oxide, Oxygen

c) Calcium, Magnesium.

d) bad

e) Hydrogen

(3.) a) Bleaching powder is used to make water bacteria free.

Ans. True

c) Solubility of gases in water increases with temperature.

Ans. False

Supporting Statement: Solubility of gases in water decrease with increase temperature.

d) Density of ice is more than the density of water.

Ans. False.

Density of water is more than the density of ice.

e) Heating water kept at 0oC leads to an increase in volume.

Ans. True.

(4) (1) Why is there a water crisis even though 3/4th of the Earth’s surface is covered by water?

Ans. Many substances like common salt and other minerals are present in ocean water in large quantities.

Due to these the water becomes salty or saline. It cannot be used for drinking, bathing, washing clothes or irrigation. Water present as icebergs is pure though it cannot be used easily. Of the total water available on earth, the quantity of water which can be used by human beings is very small.

(8) What is meant by rain water harvesting?

Ans. Collecting Rainwater for use as per requirement is called rain water harvesting. The rain falling on house roofs is collected and routed to pits in the ground through pipes. This pit is of an appropriate shape with concrete walls.

Updated: October 11, 2020 — 12:18 am

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