Home » CHAPTER 4 Air


Q1. Answer the following question briefly.

I). What is atmosphere?

Ans. Atmosphere is a thin blanket of air that surrounds the earth. It protects us from the harmful rays of the sun.

Ii). Which two gases make the bulk of the atmosphere?

Ans. Nitrogen and oxygen.

Iii). Which gas creates green house effect in the atmosphere?

Ans. Carbondioxide.

Iv). What is weather?

Ans. Weather is hour to hour, day to day conditions of the atmosphere.

V). Name three types of rainfall.

Ans. Convectional rainfall, orographic rainfall and cyclonic rainfall.

Vi). What is air pressure?

Ans. The pressure of air or weight of air on earth surface is known as air pressure.

Q2. Tick the correct answer.

I). Which of the following gases protects us from harmful sunrays?

A). Carbon dioxide

B). Nitrogen

c). Ozone                        

Ii). The most important layer of the atmosphere is-

a). Troposphere  

B). Thermosphere

C). Mesosphere

Iii). Which of the following layers of the atmosphere is free from clouds?

A). Troposphere

b). Stratosphere

C). Mesosphere

Iv). As we go up the layers of the atmosphere, the pressure-

A). Increases

b). Decreases

C). Remains the same

V). When precipitation comes down to the earth in the liquid form, it is called-

A). Cloud

b). Rain

C). Snow

Q3. Match the following.


I) trade winds       –       permanent wind

Ii) loo                     –       local wind

Iii) monsoon         –       seasonal wind

Iv) wind                 –      horizontal movement of air

Q4. Give reasons.

I) wet clothes take longer time to dry on a humid day?

Ans. On a humid day the air is full of water vapour. Hence evaporation is very slow. This is the reason why wet clothes take longer time to dry on a humid day.

Ii) amount of insolation decreases from equator towards poles? Ans. The sun rays falls straight on equator but become slanting on poles so there is less hotness as compared to equator.