SECTION-3

##### Q21. A process in which no heat is supplied or rejected and entropy is constant is known as

(b) isentropic process
(c) polytropic process
(d) isothermal process.

Ans:(b) isentropic process

##### Q22. If cyclic ∫ dQ/T >0, the cycle is

(a) reversible
(b) irreversible
(c) impossible
(d) none of the above.

Ans:(c) impossible

##### Q23. A heat engine is supplied with 300 kcal/sec of heat at constant fixed temperature of 250°C. If 200 kcal/sec are rejected at 10°C, the cycle is

(a) reversible
(b) irreversible
(c) impossible
(d) none of the above.

Ans:(b) irreversible

##### Q24. Entropy itself cannot be defined but change of entropy is defined for a reversible process as

(a) heat added system/absolute temperture
(b) (heat added) × (absolute temperature)
(c) absolute temperature/heat added
(d) none of the above.

Ans:(a) heat added system/absolute temperture

##### Q25. At a temperature of 227°C the heat supplied to an engine is 250 kcal per second. Heat rejected takes place at a constant temperature of 27°C. If heat rejected 200 kcal/sec. Then applying Clausius inequality, determine whether the process would be

(a) irreversible
(b) reversible
(c) impossible
(d) none of the above.

Ans:(a) irreversible

##### Q26. If in the above question, the heat rejected is 100 kcal/ sec, the process would be

(a) irreversible
(b) reversible
(c) impossible
(d) none of the above.

Ans:(c) impossible

##### Q27. The work done, in a non-flow reversible process when volume (V)changes from 1 m3 to 3 m3, and p = (–3V + 12) kgf/cm2, is

(a) 1 × 104 kgf-m
(b) 12 × 104 kgf-m
(c) 12 kgf-m
(d) 20 kgf-m.

Ans:(b) 12 × 104 kgf-m

##### Q28. A process will be reversible if it involves

(a) friction
(b) unresisted expansion
(c) heat transfer with a finite temperature difference
(d) none of the above.

Ans:(d) none of the above.

##### Q29. The condition for a cycle to be irreversible is

(a) cyclic ∫ dQ/T <0
(b) cyclic ∫ dQ/T =0
(c) cyclic ∫ dQ/T >0
(d) none of the above.

Ans:(b) cyclic ∫ dQ/T =0

##### Q30. The condition for a cycle to be irreversible is

(a) cyclic ∫ dQ/T <0
(b) cyclic ∫ dQ/T =0
(c) cyclic ∫ dQ/T >0
(d) all of the above.

Ans:(a) cyclic ∫ dQ/T <0

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##### Read More Sections of Thermodynamics Objective Questions

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Thermodynamics Objective Questions – Section-1

Thermodynamics Objective Questions – Section-2

Thermodynamics Objective Questions – Section-3

Thermodynamics Objective Questions – Section-4