#### NCERT Solutions for Class 6th: Ch 15 Air Around us Science

Page No: 153

Exercises

1. What is the composition of air?

Air contains some gases mainly nitrogen, oxygen, small amount of carbon dioxide, water vapour and
dust particles.

2. Which gas in the atmosphere is essential for respiration?

Oxygen gas in the atmosphere is essential for respiration.

3. How will you prove that air supports burning?

Step I: Two shallow containers are taken and burning candles are fitted into it.
Step II: Now, water is filled in the container at two different levels.
Step III: Both the candles are then covered with glass.
Step IV: After sometimes, we observed that the candles having less water in its container lights off.

This happened because the container having more water contains more oxygen and therefore it burnt for more time. Thus, it is proved that air supports burning.

4. How will you show that air is dissolved in water?

Step I: Water in a pan is taken.
Step II: It is now boiled on stove.
Step III: We will observe tiny bubbles of water visible coming out from the bottom of the pan.

These tiny bubbles are coming due to the air dissolved in water. Thus, this proves that air is dissolved in water.

5. Why does a lump of cotton wool shrink in water?

The lump of cotton contains air in it. When it comes in contact with water, the air pushed out from the vacant space and dissolved in water and thus a lump of cotton wool shrink in water.

Page No: 154

6. The layer of air around the earth is known as ___________.

The layer of air around the earth is known as atmosphere.

7. The component of air used by green plants to make their food, is ___________.

The component of air used by green plants to make their food, is carbon dioxide.

8. List five activities that are possible due to the presence of air.

Five activities that are possible due to the presence of air:
(i) Helps in seed dispersal and pollination.
(ii) Sailing of ships.
(iii) Flying of the birds and kites.
(iv) Gives us oxygen to respire.
(v) Helps in the rotation of windmill.

9. How do plants and animals help each other in the exchange of gases in the atmosphere?