Air enters an adiabatic turbine at 2.8 mpa, 673.15 k, expands at 150 kpa. assume an isentropic efficiency of .90 for the turbine. (a) assume air to be an ideal gas with constant specific heats at the anticipated average temperature of 400 k. is this assumption valid, and why? (b) solve for work output per unit of mass due to the turbine. (c) determine the exit temperature of the turbine. (d) draw the t-s diagram for the air passing through the turbine with processes. (e) what is the rate of entropy generation in the turbine.