Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Polar areas have high atmospheric pressure.
Reason (R): These areas receive minimum sunshine throughout the year.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are true but (R) is not the correct explanation of (A)
Assertion (A) — True. Around both poles lie the polar high-pressure belts. The air there is extremely cold and therefore dense; it sinks and piles up near the ground, so the surface pressure stays high. Because they come from low temperature, these belts are called thermally induced.
Reason (R) — True. The polar areas receive the least solar energy of any part of the Earth: the Sun stays low in the sky even in summer, and for months in winter it does not rise at all.
Does (R) explain (A)? As per the answer given by NTA, no. The pressure is high because the air is cold and dense and sinks; the Reason speaks only of sunshine. In summer the poles in fact get sunshine round the clock for months, yet they stay cold because the Sun’s rays fall at a very slanting angle and spread their heat over a large area. So the Reason states a fact about the poles without giving the cause of the high pressure.
Note: One can argue that the little energy the poles get from the Sun is what keeps their air cold, and that the cold air is what raises the pressure; on that reading the Reason would explain the Assertion, which is Option (1). The answer given by NTA treats the Reason as too indirect, since the pressure comes from the cold, sinking air itself.