One mole of an ideal monatomic gas has initial temperation T0, is made to  go through the cycle abca shown in the given figure. If U denotes the internal energy, then choose the correct alternative.

One mole of an ideal monatomic gas (initial temperature T0) is made to go through the cycle abca shown in figure. U denotes the internal energy.For the process ab, P0V0T0=2P0V0T0Tb=2T0Tb>Ta⇒Ub>UaUb−Ua=CvΔT=3R22T0−T0=3RT02For the process bc,P02V02T0=2P02V0TC⇒TC=4T0Tc>T0Uc−Ub=3R24T0−2T0=3RT0For the process ca,Uc−Ua=3R24T0−T0=9RT02