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"Heat cannot by itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of

Asked in JEE Main 2003 · Second Law and Reversibility

(1) the second law of thermodynamics
(2) conservation of momentum
(3) conservation of mass
(4) the first law of thermodynamics

Answer: (1) the second law of thermodynamics

Step-by-step solution

That heat does not flow unaided from cold to hot is the Clausius statement of

the second law of thermodynamics.

Why the other options are wrong

(2) comes from momentum conservation says nothing about the direction of heat flow
(3) comes from mass conservation says nothing about it either
(4) comes from the first law permits the reverse flow; it is the second that forbids it

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