4. A piston-cylinder system initially contains 0.25 kg of ideal gas at P1=8 bar and V=0.02 m³ (State1). After a polytropic expansion process described by PV drops to 2 bar

(State 2). During this process, heat transfer between the system and environment occurs.The specific internal energy of the gas decreases by 55 kJ/kg. Ignoring the change in the kinetic energy and potential energy of this system, determine (12 points)=C, the pressure ofgas in the cylinder (a) the boundary work done by the gas, in kJ (6 points) (b) the heat transfer during the process, in kJ (6 points)