An internally reversible turbine is used to extract work from high energy argon. At the inlet of the turbine, the argon is at 420 K and 1190 kPa. The pressure at the exit is 60 kPa. What is the maximum amount of work that can be produced if the expansion process is:

(a) isothermal? $\displaystyle \frac{\text{kJ}}{\text{kg}}$

(b) polytropic (with n=1.7)? $\displaystyle \frac{\text{kJ}}{\text{kg}}$

(c) isentropic? $\displaystyle \frac{\text{kJ}}{\text{kg}}$