A system undergoes a change from a given initial state to a given final state either by an irreversible process or by a reversible process, then (where, Δ S1 and Δ SR are the entropy changes of the system for the irreversible and reversible processes respectively) ?

Related Mcqs:

1. Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400°C (entropy = 6.65 kJ/kg K) to 150 kPa) (entropy of saturated liquid = 1.4336 kJ/kg. K, entropy of saturated vapour = 7.2234 kJ/kg. K) The exit condition of steam is_______________?

   A. Superheated vapour
   B. Partially condensed vapour with quality of 0.9
   C. Saturated vapour
   D. Partially condensed vapour with quality of 0.1

2. On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (∂P/∂V)s and the slope of the reversible isothermal line (∂P/∂V)T are related as (where, y = Cp/Cv) ?

   A. (∂P/∂V)S = (∂P/∂V)T
   B. (∂P/∂V)S = [(∂P/∂V)T]Y
   C. (∂P/∂V)S = y(∂P/∂V)T
   D. (∂P/∂V)S = 1/y(∂P/∂V)T

3. The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is_________________?

   A. R loge 4
   B. R log10 4
   C. Cv log10 4
   D. Cv loge 4

4. The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible _____________ process?

   A. Isobaric
   B. Isothermal
   C. Adiabatic
   D. None of these

5. Entropy change for an irreversible process taking system and surrounding together is___________________?

   A. 0
   B. > 0
   C. < 0
   D. None of these

6. High pressure steam is expanded adiabatically 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. Δ H = 0 and ΔS = 0
   B. Δ H ≠ 0 and ΔS = 0
   C. Δ H ≠ 0 and ΔS ≠ 0
   D. Δ H = 0 and ΔS ≠ 0

7. Entropy change in case of reversible adiabatic process is________________?

   A. Minimum
   B. Zero
   C. Maximum
   D. Indeterminate

8. Entropy change for an irreversible isolated system is__________________?

   A. ∞
   B. 0
   C. < 0
   D. > 0

9. A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the _____________ mean of P1 and P2.(where, P1 and P2 are initial and final pressures respectively) ?

   A. Logarithmic
   B. Arithmetic
   C. Geometric
   D. Harmonic

10. During a reversible isothermal expansion of an ideal gas, the entropy change is___________________?

    A. +ve
    B. 0
    C. -ve
    D. ∞