A diathermic piston divides adiabatic cylinder of volume V0 into two equal parts as shown in the figure. Both parts contain ideal monoatomic gases. The initial pressure and temperature of gas in left compartment are P0 and T0 while that in right compartment are 2P0 and 2T0. Initially the piston is kept fixed and the system is allowed to acquire a state of thermal equilibrium.

If the pin which was keeping the piston fixed is removed and the piston is allowed to slide slowly such that a state of mechanical equilibrium is achieved. The volume of left compartment when piston is in equilibrium is