Assertion: The heat supplied to a system is always equal to the increase in its internal energy
Reason: when a system changes from one thermal equilibrium to another, some heat is absorbed by it.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false

Answer

D

Explanation

According to first law of thermodynamics, `DeltaQ=DeltaU+DeltaW = DeltaU + PDeltaV`. If heat is supplied in such a manner that volume does not change `DeltaV=0`, i.e.. isochoric process, then whole of the heat energy supplied to the system will increase internal energy only. But, in any other process it is not possible.
Also, heat may be absorbed or evolved when state of thermal equilibrium changes.