DAV question answer of air and around us chapter 4
Answers
Answer:
Question 1.
Define the term atmosphere.
Answer:
Blanket of air surrounding the earth is known as the atmosphere.
Question 2.
How do all living beings depend on the atmosphere for their survival?
Answer:
All living beings depend on the atmosphere for their survival.
Atmosphere provides them the air they breathe.
It protects them from the harmful effects of the sun’s rays.
Without its protection, they would be baked alive by the heat of the sun during day and get frozen during night.
Question 3.What is green house effect?
Answer:
Carbon dioxide in the atmosphere traps the heat radiated from the earth creating a green house effect. This makes the temperatures livable. Without this earth would have been too cold to live. But the increased emissions from vehicles and factories increases the temperature leading to global warming.
Question 4.
What is global warming? What is its affect?
Answer:
When the heat retained through greenhouse gas increases the temperature of the earth, it causes global warming:
The plants maintain the balance of gases. However this balance is upset by burning fuels such as coal, petroleum oil and large scale deforestation.
This rise in temperature causes the snow in coldest parts to melt.
As a result the sea level rises causing floods in the coastal areas.
This may bring changes in weather and climate leading to extinction of certain plants and animal species.
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