Cyclic Process

As emphasised in NCERT Class 11, Chapter 12 (Thermodynamics), internal energy is a state function, meaning its value depends only on the current state of the system, not on the path taken to reach it. In a complete cycle the gas returns to its initial state, so the initial and final internal energies are identical and $\Delta U_{\text{cycle}}=0$. Applying the First Law over the cycle, $$\begin{gathered} \Delta Q=\Delta \\ cup+\Delta W=0+\Delta W \end{gathered}$$, so the net heat absorbed equals the net work done by the gas. The option that $\Delta U$ equals the net heat absorbed is wrong because that heat instead equals the net work, not the internal energy change. The option that $\Delta U$ equals the net work is wrong for the same reason; over a cycle $\Delta U$ is strictly zero. The option that it is always negative for a clockwise cycle confuses the net work (positive for clockwise on a P-V diagram) with internal energy. A consistency check: since $U$ depends only on state variables like $T$ for an ideal gas, returning to the same $T$ guarantees the same $U$, so the cyclic change must vanish.