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Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Hydrogen is the most abundant element in the Universe, but it is not the most abundant gas in the troposphere. Reason R: Hydrogen is the lightest element. In the light of the above statements, choose the correct answer from the options given below:

1. A is true but R is false
2. Both A and R are true and R is the correct explanation of A
3. A is false but R is true
4. Both A and R are true but R is NOT the correct explanation of A

Correct answer: Both A and R are true and R is the correct explanation of A

Solution

The assertion is correct as hydrogen is indeed the most abundant element in the universe, while in the troposphere, nitrogen and oxygen are more prevalent gases. The reason is also true since hydrogen's lightness contributes to its tendency to rise and escape the troposphere, explaining why it is not the most abundant gas there.

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