Air is compressed from room conditions to a specified pressure in a reversible manner by two compressors: one isothermal and the other adiabatic. If the entropy change of air ∆sisot during the reversible isothermal compression, and ∆sidia during the reversible adiabatic compression, the correct statement regarding entropy change of air per unit mass is
(a) ∆sisot = sadia = 0
(b) ∆sisot = ∆sadia > 0
(c) ∆sadia > 0 (d) ∆sisot <0
(e) ∆sisot = 0