Aquantity of air undergoes a cycle consisting of the following internally reversible processes in a closed system. process 1-2: constant-volume heating from an initial state at pi 0.1 mpa, ti - 27 °c, and v1 0.02 m3 to p2 0.4 mpa process 2-3: constant-pressure cooling process 3-1: isothermal heating to initial state employing the ideal gas model with variable specific heats, find (a) entropy change in each process of the cycle, (b) heat and work involved in each process of the cycle, (c) is this cycle a power cycle or refrigeration cycle?