This isn't an actual problem, it's just a question based on my reading. Reif says "If the external parameters of a thermally isolated system are changed quasi-statically by any amount, ΔS = 0."
I don't understand why it has to be thermally isolated. Looking at the entropy relation
[tex] dS = dq/T [/tex]
There isn't any work in there, and the derivation didn't set work = 0. So if a system undergoes a reversible process and dQ is non-zero, it seems that work also has no effect on the entropy change?