The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?
AIce is a bad conductor of heat
BSince the surface of the lake is at the same temperature as the air, no heat is lost
CThe density of water is maximum at $4^{\circ}\mathrm{C}$
DNone of the statements (a), (b) and (c) given above is correct
Answer & Solution
Correct answer: C. The density of water is maximum at $4^{\circ}\mathrm{C}$
UPSC CSE Prelims 2011 (GS-I, Set A), Q.50. Official answer key: C.
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