NCERT 6th Class (CBSE) Science: Air Around Us

Question: List five activities that are possible due to presence of air.

Answer: The activities that are possible due to the presence of air are:

1. To make a simple firki
2. To make a weather cock
3. To breathe for survival
4. For burning of substance
5. For photosynthesis

Question: How do plants and animals help each other in exchange of gases in the atmosphere?

Answer: Animals and plants use oxygen from air during respiration and release carbon dioxide gas in air. But green plants also release oxygen gas by using carbon dioxide during photosynthesis. Thus, we can say that animals and plants help each other in exchange of gases.

Question: Name the main component of air.

Answer: Nitrogen gas

Question: What is the source of oxygen gas in air?

Answer: Photosynthesis by green plants is source of oxygen gas in air.

Question: What is the percentage of nitrogen in air?

Answer: 78.1%

Question: What is the percentage of oxygen in air?

Answer: 20.9%

Question: What is the source of carbon dioxide in air?

Answer: Respiration by animals and plants and burning of fuel.

Question: Mention one necessary condition for the combustion to take place.

Answer: Presence of air.

Question: Why is air considered as a mixture?

Answer: Air contains oxygen and nitrogen as its major constituents of air. These gases retain their properties in air. So the air is called a mixture.

Question: Name the major gas present in the (a) inhaled air (b) exhaled air.

Answer: (a) Oxygen (b) Carbon dioxide.

Question: Write the necessary conditions for rusting of iron to take place.

Answer: Rusting of iron takes place in the presence of moisture and air. So the presence of air and water vapour in air are two necessary conditions for rusting of iron.

Question: Name a device which uses wind energy to generate electricity.

Answer: Windmills use the wind energy to convert wind energy into electrical energy

Question: What is wind energy? Mention its two advantages.

Answer: Blowing air is called wind. Wind possesses kinetic energy. The kinetic energy possessed by wind is called wind energy.

Uses of Wind Energy are:

1. Wind energy is used to pump the ground water.
2. Wind energy is used to generate electricity with the help of windmills.

Question: Mention two uses of air.

Answer: The two uses of air are as below:

1.  For respiration all organisms need air.
2.  For burning of any substance air is needed.