Chapter 4 Air

Chapter 4 – Air



Question 1:

Answer the following questions.

(i) What is atmosphere?

(ii) Which two gases make the bulk of the atmosphere?

(iii) Which gas creates greenhouse effect in the atmosphere?

(iv) What is weather?

(v) Name three types of rainfall?

(vi) What is air pressure?


(i) Atmosphere is a thin blanket of air that surrounds the earth. It protects us from the harmful rays of the sun. It consists of several gases in which nitrogen and oxygen occupy the major portion.

(ii) Nitrogen (78%) and oxygen (21%) make the bulk of the atmosphere.

(iii) Carbon dioxide creates greenhouse effect in the atmosphere.

(iv) Weather is hour-to-hour, day-to-day condition of the atmosphere.


  • Convectional rainfall
  • Orographic rainfall
  • Cyclonic rainfall.

(vi) The pressure exerted by the weight of air on the earth’s surface is known as air pressure.


Question 2:

Tick the correct answer.

(i) Which of the following gases protects us from harmful sun rays?

(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


(i) Ozone

(ii) Troposphere

(iii) Stratosphere

(iv) Decreases

(v) Rain


Question 3:

Match the following.

(i) Trade Winds(a) Incoming Solar energy
(ii) Loo(b) Seasonal wind
(iii) Monsoon(c) Horizontal movement of Air
(iv) Wind(d) Layer of ozone gas
 (e) Permanent wind
 (f) Local wind



(i) Trade Winds(e) Permanent wind
(ii) Loo(f) Local wind
(iii) Monsoon(b) Seasonal wind
(iv) Wind(c) Horizontal movement of Air


Question 4:

Give reasons.

(i) Wet clothes take longer time to dry on a humid day?

(ii) Amount of insolation decreases from equator towards poles?


(i)  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) Insolation comes through vertical rays on equator. Thus, it covers up less space but we feel more heat there when it goes up from equator towards poles, the sun rays become slanting. Needless to say that slanting rays come on the earth covering longer distance. Although these slanting rays heat up more space, the degree of hotness is felt less. This is the reason why amount of insolation decreases from equator towards poles.


Question 5:

For fun.

(i) Solve this Crossword puzzle with the help of given clues:




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