Air in a piston–cylinder assembly undergoes a process from state 1, where T1 5300 K, p1 5100 kPa, to state 2, where T2 5500 K, p2 5650 kPa. Using the ideal gas model for air, determine the change in specific entropy between these states, in kJ/kg.K, if the process occurs (a) without internal irreversibilities, (b) with internal irreversibilities.