Question

For a cyclic thermodynamic process

• A. \(Q=-W\) and \(\Delta U\neq 0\)
• B. \(Q=0\) and \(\Delta U=0\)
• C. \(Q\neq 0,\Delta U\neq 0\)
• D. \(Q=W\) and \(\Delta U=0\)

Hint:

Internal energy is a state function, so its change over a complete cycle is zero.

Answer 1

The Correct Option is D

Step 1: Elimination
A cycle returns to the starting state, so $\Delta U\neq 0$ cannot be correct. This removes the first and third options.

Step 2: Check Q
$Q=0$ would mean no work is done, but a cycle usually does net work. So the second option is wrong.

Step 3: Result
By the first law, $Q=W$ with $\Delta U=0$.

Final Answer:
The correct description is Q equals W with no change in internal energy. \[ \boxed{\text{(D) }Q=W\text{ and }\Delta U=0} \]