The internal energy of a gas is given by U = 2PV. It expands from V0 to 2V0. Against a constant pressure P0 , the heat absorbed by the gas in the process is

As it is a constant pressure process volume becomes double temperature also becomes double so increase in temperature is T0.given U = 2PV; ∆U =  2P0V0Work done at constant pressure  P02V0-V0 =P0V0dQ = dU + dW = 3P0V0