Question

A system is taken from a given initial state to a given final state along various paths represented on a PV-diagram. The quantity that is independent of the path is:

• A. amount of heat transferred $Q$
• B. amount of work done $W$
• C. $(Q-W)$
• D. None of these

Answer 1

Answer: (C)

$(Q-W)$

From the first law of thermodynamics,
Q = U + W
Thus, $Q-W=U$
Since, internal energy is a state variable and its value depends only on the initial and final states, and not on the path taken,
Thus, Q - W will have the same value irrespective of the path taken