High pressure steam is expanded adiabati-cally and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process:

A. ΔH = 0 and ΔS = 0

B. ΔH ≠ 0 and ΔS = 0

C. ΔH ≠ 0 and ΔS ≠ 0

D. ΔH = 0 and ΔS ≠ 0

Answer: Option B

Solution(By Examveda Team)

For a reversible adiabatic process the entropy change is zero since $$dS = \frac{{\delta Q}}{T}$$
But the enthalpy change need not be zero since the internal energy and pressure energy may vary during the process.