The two uses of air are given as follows:
(i) Air is used to inflate the tyres of vehicles.
(ii)Airis used by plants and animals for respiration.

As we move up in the atmosphere, the air becomes thin. Because of this, mountaineers feel little difficulty in inhaling- oxygen. To overcome this problem they carry oxygen cylinders with them.

The air consists of following:
Nitrogen (78%), Oxygen (21%), Carbon dioxide, water vapours, dust and other gases.

Aquatic animals take the dissolved oxygen/air in water for respiration.

The amount of oxygen decreases at high altitude. So, for normal breathing, mountaineers carry oxygen cylinders with them, while climbing high mountains.

Take a burning candle which is fixed in a tumbler containing water. The candle is covered by an inverted glass. After some time, the covered candle gets extinguished and water rises upto 1/5th of the glass. It shows that air supports burning.

As we go up above the sea-level, the atmospheric pressure goes on decreasing and the amount of oxygen also decreases at higher altitude.

Carbon dioxide does not support combustion. When sprayed on burning object, it stops the supply of oxygen and extinguishes fire.

Air generates electricity through windmills.

1% of air includes carbon dioxide (C02), water vapours , helium, hydrogen, dust particles and smoke.

To prevent inhalation of smoke given out by automobiles, policemen use masks.

Plants release oxygen during photosynthesis.

Dissolved air helps aquatic animals for breathing.

Oxygen.

Respiration by animals and plants and burning of fuel.