Air is compressed steadily by a reversible compressor from 100 kPa and 300 K to 900 kPa. Determine the compressor work per unit mass (answers in kJ/kg) for (a) isentropic compression with k = 1.4, (b) polytropic compression with n = 1.3, (c) isothermal compression. Take c_{p} = 1.005 kJ/kg·K, R = 0.287 kJ/kg·K.