Summary of air

Solved exercise of air


Air being a mixture of many gases is very essential for sustaining the life of animals and plants, air is not visible, but its presence can be felt.Air is one of the natural resources. The earth is surrounded by layers of air called atmosphere.Air is a mixture of nitrogen(78%), oxygen(21 %) carbon dioxide(0.04%) water vapour, noble gases and dust particles.(0.96%)

Uses of Air

  • We use oxygen in air for respiration.
  • We cannot live without respiration.
  • Animals and plants also need oxygen for respiration.
  • Oxygen is necessary for fuels to burn.

Air pollution

Air pollution Mixing chemicals, dust, micro organisms which are harmful to man and other organisms into air is called Air pollution.

Measures to be followed  to prevent air pollution are as follows.

  • Preventing the mixing up of chemical wastes discharged  by factories, with air.
  • Installing tall chimneys in factories so that the smoke can be released at a higher altitude.
  • Using gaseous fuel instead of coal, diesel and petrol
  • Using public transport.
  • Using alternative energy sources like solar energy, hydroelectric power and wind power.
  • Avoiding burning of substances near civilian areas.           

Wind Energy

Wind energy is a form of solar energy wind is used to generate electricity Moving air is called wind.

Uses of Wind Energy

  • It is  used for sailing, flying a kite, and even generating electricity.
  • Roofs of houses are carried away by strong wind. While walking on a street, sometimes we feel the wind pushing us. Clothes hung out to dry will flutter when the wind blows.
  • A vehicle cannot move if the air inside the tyre comes out. Coconut trees swing in strong winds.


Answer the following questions.

1.Which gas is the major component of air?

Ans:Nitrogen gas is the major component of air.

2.What percentage of gas required for our respiration is present in the air?

Ans:We use oxygen in air for respiration an constituent in air is 21% other are 78% and 1% other gases.

3.What is the normal percentage of carbon dioxide in  air?

Ans:0.04% is the normal percentage of carbon dioxide in  air.

4.Which is the least component present in air?

Ans:Air consist of various gases.the least component in air is helium which is listed in other air.

5.What happens when the tyre of a vehicle gets punctured?

Ans:Air slowly released, a vehicle cannot move if the air inside the tyre comes out.

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