JEE Main · 2023 · 10 Apr 2023 · Shift 2 · Heat & Thermodynamics

In an adiabatic process no heat enters or leaves the gas, so $\Delta Q=0$, and the first law reduces to $\Delta U=-\Delta W$. During compression the surroundings do work on the gas, so its internal energy rises and its temperature increases, with the increase in internal energy equal to the work done on the gas. The assertion that the internal energy does not change contradicts this, because $\Delta U$ is non-zero for adiabatic compression. The statement that is not true is the one claiming there is no change in the internal energy.