Steam at 4 MPa, 600oC enters an insulated turbine operating at steady state with a mass flow

Question:

Steam at 4 MPa, 600oC enters an insulated turbine operating at steady state with a mass flow rate of 5 kg/s and exits at 200 kPa. Determine.
(a) The maximum theoretical power that can be developed by the turbine.
(b) The corresponding exit temperature. Also determine.
(c) The isentropic efficiency if steam exits the turbine at 220oC.