Official Answer Key & Detailed Solution
Ready to check the official UPSC Answer Key?
Click any option above to test yourself under exam conditions, or reveal the explanation directly.
Correct Answer: Option (B) — Both A and R are true but R is not a correct explanation of A
Concept & Option Breakdown
Standard Reference VerifiedAssertion (A) is true: Weight $W = mg = \frac{G M m}{(R + h)^2}$. As altitude ($h$) increases, distance from Earth's center increases, so $g$ decreases and weight diminishes. Reason (R) is true: The Earth is an oblate spheroid (flattened at the poles and bulging at the equator). However, R is not the correct explanation of A, because the variation of weight with altitude is a direct consequence of the inverse-square law of gravitation with distance from the center, which applies even on a perfectly spherical planet.
Decrease in weight with altitude occurs solely due to increasing distance ($R+h$), regardless of Earth's nonspherical shape.
Practice Full-Length & Sectional Prelims Mocks on this Interface
50 simulated tests in the APT Prelims Test Series (₹1,493) or 1-on-1 Mentorship with Avinash Sir.