One mole of an ideal monoatomic gas undergo a thermodynamic cyclic process ABCDA as shown in internal energy (U) and density (ρ) graph.The corresponding pressure (p) versus volume (V) graph is

(b) AB and CD are Isothermal process while BC and DA are isochoric process. For AB, U constant and ρ increases. Constant U means constant temperature. From ideal gas equation.p=ρRTM ∴ ρ increases, p increases∴ ρ=mV  It p increases, V decreasesAt constant temperature so PV = K isothermal processFor BC, U increases at constant density. Constant density, constant volume and if T increases (as U increases) pressure also increases. Similar for rest two processes.So, final p – V variation is