Determine the net change in entropy.

Question

2 kg of air is first compressed from state 1 at 13.75 N/cm² and 5⁰C to state 2 at 48 N/cm² and 283 ⁰C. It is then throttled to state 3 until its pressure is again 13.75 N/cm². Finally it is cooled at constant pressure to state 4 until its volume becomes 50% of that before the cooling process. Determine the net change in entropy.                                                                                                       20

(R= 0.291 N.m/g.K; C_p = 1.004 kJ/kg.K)