Hot combustion gases enter an adiabatic nozzle of a turbojet engine at 230 kPa, 627°C and 60 m/s and exit at 70 kPa and 450°C. Assuming the surroundings to be at 20°C, calculate: (a) the exit velocity, (b) the exergy destroyed per kg of combustion gases flowing, and (c) the second law efficiency. Assume properties of combustion gases are: C₂ = 1.15 kJ/kg∙K; k = 1.3; and Gas Constant R = 0.265 kJ/kg-K