Physics - Heat & Thermo Question with Solution | TestHub

T = constant (isothermal process), so $\Delta U=0$ and $P_A{V}_A=P_B{V}_B=nRT$. Compression from A to B (density increases) needs work done on the gas, so $W_{A\to B}<0$ (work done by the gas), and $P_B>P_A$ since ${\rho }_B>{\rho }_A$ at the same T.