4) Two kilograms of air within a piston-cylinder assembly execute a Carnot power cycle with maximum and minimum temperatures of 750 K and 300 K respectively. The heat transfer to the air during the isothermal expansion os 60 kJ. At the end of the isothermal expansion, the pressure is 600 kPa and the volume is 0.4 m^3. Assuming the ideal gas model for the air determine:
(a) the thermal efficiency

(b) the pressure and the volume at the beginning of the isothermal expansion, in kPa and m^3 respectively

(c) the work and heat transfer for each of the four processes in kJ

(d) sketch the cycle on a p-V coordinates