1. One mol of air is compressed from an ideal state of 1 bar and 25°C to a final state of 5 bar and 25 °C by three different mechanically reversible processes in a closed system: Assume air to be an ideal gas with the constant heat capacity，Cv= (5/2)R and Cp = (7/2)R，in which R is gas constant and R = 8.314 J/mol.K. Calculate the work required, heat transferred, and the changes in internal energy and enthalpy of the air for each process. (30 points)
(a) Heating at constant volume followed by cooling at constant pressure.