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With reference to “water vapour,” which of the following statements is/are correct

With reference to “water vapour,” which of the following statements is/are correct?
1. It is a gas, the amount of which decreases with altitude.
2. Its percentage is maximum at the poles.
Select the answer using the code given below:

(a)

1 only

(b)

2 only

(c)

Both 1 and 2

(d)

Neither 1 nor 2

Answer:

(a)

Core Books/NCERT

Explanation

Statement 1 is correct : The water vapour content of the atmosphere depends on the air pressure, and decreases as altitude increases and pressure decreases. So, as altitude increases, the ability of the atmosphere to absorb thermal radiation and radiate it back to the Earth’s surface lessens. Statement 2 is incorrect : As it decreases with altitude, it is minimum at poles and ,maximum at the equator.