5.14 A power cycle receives QH by heat transfer from a hot reservoir at TH = 1200 K and rejects energy QC by heat transfer to a cold reservoir at TC = 400 K. For each of the following cases, determine whether the cycle operates reversibly, operates irreversibly, or is impossible. (a) QH = 900 kJ, Wcycle = 450 kJ (b) QH = 900 kJ, QC = 300 kJ (c) Wcycle = 600 kJ, QC = 400 kJ (d) η = 75%