Given below are two statements, an Assertion (A) and a Reason (R). Choose the correct answer.
Assertion (A):The heat is trapped close to the Earth's surface mostly by naturally occurring gases such as carbon dioxide, methane, nitrous oxide and water vapour, and by synthetic fluorinated gases.
Reason (R):These gases make a sort of blanket around the Earth, keeping the planet warmer than it would be without them.
ABoth (A) and (R) are true and (R) is the correct explanation of (A) ✓ Correct
BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
C(A) is true, but (R) is false
D(A) is false, but (R) is true
Correct answer: (A) Both (A) and (R) are true and (R) is the correct explanation of (A)
Explanation
Both the assertion and the reason are true, and the reason explains the assertion.
The assertion lists the heat-trapping gases as carbon dioxide, methane, nitrous oxide, water vapour and synthetic fluorinated gases.
The reason explains that these gases wrap the earth like a blanket, keeping it warmer than it would otherwise be.
Because they absorb and re-emit heat near the surface, the planet stays warm just as the assertion states.
The reason thus gives the blanketing mechanism behind the trapping the assertion describes.
Without this natural warming the earth's average surface would be well below freezing.
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