Class 7 Geography Chapter 4 Practice Question Answers - Air

Q1. The quantity of oxygen in the air is:
(a) 78%
(b) 21%
(c) 15%
(d) 10%
Ans: (b)

Q2. Ozone layer is found in:
(a) Troposphere
(b) Mesosphere
(c) Thermosphere
(d) Stratosphere
Ans: (d)

Q3. Which gas creates a greenhouse effect?
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Carbon dioxide
Ans: (d)

Q4. Ionosphere is a part of:
(a) Troposphere
(b) Mesosphere
(c) Thermosphere
(d) Stratosphere
Ans: (c) 

Q5. What was invented by Anders Celsius?
(a) Barometer
(b) Thermometer
(c) Rain gauge
(d) None of the above
Ans: (b)

Q6. Which winds change their direction in different seasons?
(a) Permanent winds
(b) Seasonal winds
(c) Local winds
(d) None of the above
Ans: (b)

Q7. Which layer is the upper most layer?
(a) Troposphere
(b) Mesosphere
(c) Thermosphere
(d) Exosphere
Ans: (d)

Q8. Which gas is available most plentiful in the air?
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Carbon dioxide
Ans: (a)

Q9. Degree of hotness and coldness of the air is called:
(a) Humidity
(b) Pressure
(c) Temperature
(d) Insolation
Ans: (c)

Q10. Atmospheric pressure is measured by:
(a) Barometre
(b) Thermometer
(c) Rain gauge
(d) None of the above
Ans: (a)

Q11. Which of the following gases protects us from harmful sun rays?
(a) Carbon dioxide
(b) Nitrogen
(c) Ozone
(d) All of these
Ans: (c)
One important feature of stratosphere is that it contains a layer of ozone gas. We know that it protects us from the harmful effect of the sun rays.

Q12. In which direction the wind blows constantly throughout the year in particular direction?
(a) Permanent winds
(b) Local winds
(c) Seasonal winds
(d) Both (a) and (b)
Ans: (a)
Permanent winds is the trade winds, westerlies and easterlies are the permanent winds. These blow constantly throughout the year in a particular direction.

Q13. In which layers all weather phenomenon occurs?
(a) Troposphere
(b) Stratosphere
(c) Thermosphere
(d) Mesosphere
Ans: (a)
Troposphere layer is the most important layer of the atmosphere. Its average height is 13 km.  The air we breathe exists here. Almost all the weather phenomena like rainfall, fog and hailstorm occur in this layer.

Q14. What is the result when the air is heated?
(a) Heavier
(b) Lighter
(c) Colder
(d) Warmer
Ans: (b)
When air is heated, it expands, becomes lighter and goes up. Cold air is denser and heavy.

Q15. Which is the most important layer of the atmosphere?
(a) Troposphere
(b) Thermosphere
(c) Mesosphere
(d) None of these
Ans: (a)
Troposphere layer is the most important layer of the atmosphere. Its average height is 13 km. The air we breathe exists here.

Q16. What is air pressure?
(a) Pressure exerted by the wind
(b) Pressure exerted by the rain
(c) Pressure exerted by the weight of air
(d) None of these
Ans: (c)
The pressure exerted by the weight of air on the earth’s surface is known as the air pressure.

Q17. Name the types of rainfall?
(a) Cyclonic
(b) Orographic
(c) Convectional
(d) All of the above
Ans: (d)
Convectional rainfall, Orographic rainfall, Cyclonic rainfall are the type of rainfall.

Q18. What do you mean by weather?
(a) Incoming solar energy
(b) All condition of the atmosphere
(c) Both a and b
(d) None of these
Ans: (b)
Weather is hour-to-hour, day-to-day condition of the atmosphere.

Q19. How ozone layer is important to us?
(a) Protect us from weather changes
(b) Protect us from harmful rays
(c) Protect us from rain
(d) None of these
Ans: (b)
It protects us from the harmful effect of the sun-rays.

Q20. Which gases make the bulk of the atmosphere?
(a) Nitrogen
(b) Oxygen
(c) Both a and b
(d) None of these
Ans: (c)
Nitrogen (78%) and Oxygen (21%) make the bulk of atmosphere.