Thermodynamics_16 Marks.... 2nd Question

Question 2:

0.2m³ of air at 4 bar and 130^oC is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02bar. The gas is then heated at constant pressure till enthalpy increases by 72.5KJ. Calculate work done and index of expansion if the above process is Polytrophic. Take C_p=1KJ/KgK     C _v=0.714KJ/Kg K..