at question b..

how can i calculate deltaS(surr)?

and i calculate deltaS(sys)=-dw/T=Pex(Vf-Vi). is it right?

5. [25] One mole of a perfect gas at 300K is isothermally compressed from a volume of 25.0L to a volume of 10.0L in a water bath. Because the water bath thermal reservoir in the surroundings is very large, T remains essentially constant at 300K during the process. Calculate S,Ssurroundings,,and Stotal for the cases below. (1) Reversible compression. (2) Compression by a constant external pressure equal to the final pressure. At the end of the process, p= pexternal. Because p=pextermal at all but the final state, the process is irreversible