Official Answer Key & Detailed Solution
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Correct Answer: Option (C) — Infrared waves are largely absorbed by water vapour that is concentrated in the lower atmosphere
Concept & Option Breakdown
Standard Reference VerifiedOption (a) is incorrect: The insolation at the equator is roughly 2.5 times that at the poles, not 10 times. Option (b) is incorrect: Infrared radiation constitutes about 49% of incoming solar radiation, not two-thirds (66%). Option (c) is correct: Atmospheric water vapor, concentrated in the lower troposphere, is a major absorber of longwave infrared radiation. Option (d) is incorrect: Infrared radiation has longer wavelengths than visible light and is not part of the visible spectrum.
Extreme multiplier claims (like '10 times') in UPSC options are frequently incorrect. Additionally, basic physics categorizes Infrared as invisible light, eliminating option (d).
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