Air and Atmosphere (7)

 Air and Atmosphere

( Class 7) 

Questions and answers:

1. What is Atmosphere?

Ans: Atmosphere is a layer of gases which is present around a celestial body.

2. Choose the correct option.

a) which gas constitutes 78 % of the atmosphere ?

i) carbon dioxide

 ii) argan 

iii) oxygen 

iv) nitrogen 

Ans: iv) nitrogen .

b) In which layer of the atmosphere does weather phenomena occur?

i) Troposphere 

ii)  stratosphere 

iii) exosphere

 iv) ionosphere

Ans:i ) Troposphere .

c) In which layer of the atmosphere does the International Space Station orbit?

i) troposphere

ii) thermosphere 

iii) exosphere

iv) stratosphere

Ans: ii) thermosphere 

d) Meteors burn out in this layer 

i) troposphere

ii) thermosphere

iii) mesosphere 

iv) stratosphere

Ans: iii) mesosphere 

e) Which one of the following gas is used by green plants during photosynthesis?

i) hydrogen 

ii) nitrogen

iii) argon 

iv) carbon dioxide

Ans: iv) carbon dioxide.

3. Fill in the blanks

1. The heat absorbed by the air inside the greenhouse is trapped inside which gives warmth to the plants during the night. 

2. Oxygen is nearly 21 percentage of the gases present in the atmosphere. 

3. Large scale tree felling will impact the availability of  carbon dioxide  on the Earth's surface.

4. In mesosphere layer meteors burn up on entering the earth's atmosphere.

4. Match the columns.

Column A	Column B
Atmosphere	Closest layer of the atmosphere
Troposphere	Outermost layer of the Earth's atmosphere.
Stratosphere	Ideal for flying jet aircrafts
Exosphere	Blanket of gases surrounding the Earth

Ans:

Column A	Column B
Atmosphere	Blanket of gases surrounding the Earth
Troposphere	Closest layer of the atmosphere
Stratosphere	Ideal for flying jet aircrafts
Exosphere	Outermost layer of the Earth's atmosphere.

5. Name the major gases which constitute the atmosphere of the Earth.

Ans : The major gases which constitute the atmosphere of the Earth are -  oxygen, argon, carbon dioxide, ozone, hydrogen and helium.

6.Why do plants need carbon dioxide?

Ans: Plants need carbon dioxide for photosynthesis.

7. Which gas is released by plants as a byproduct of photosynthesis process?

Ans: Oxygen.

8.Why we should not burn dry leaves?

Ans: We should not burn dry leaves because it release huge quantities of carbon dioxide into the air. This has harmful impact on the atmosphere.

9. In which layer of the atmosphere do weather phenomenon occur?

Ans: In Troposphere.

10. What is the upper limit of mesosphere known as?

Ans:  Mesopause.

11. How does thermosphere help in radio transmission?

Ans: Thermosphere contains electrically charged particles called ions which helps in radio transmission.

12. What are meteoroids?

Ans: Meteoroids are small rocky pieces which float freely around the Sun in outer space.

10.