# MULTIPLE CHOICE QUESTION ANSWERS ( MCQ) ON ENTROPY AND THERMODYNAMIC CYCLES

MULTIPLE CHOICE QUESTION ANSWERS ( MCQ) ON ENTROPY AND THERMODYNAMIC CYCLES

1. Entropy of a refrigerant is zero in S.I. units at a temperature of

(a) 00C

(b) -400C

(c) +1000C

(d) None

Ans: (b)

1. Change of entropy during heating at constant pressure is equal to

(a) Cpln(T2/T1)

(b) Cpln(V2/V1)

(c) Cpln(T2/T1)+ Cpln(V2/V1)

(d)None

Ans: (a)

1. Change of entropy from p1 to p2 under isothermal conditions will be

(a) Cpln(V2/V1)

(b) Cpln(p2/p1)

(c) Cpln(p2/p1) + Cpln(V2/V1)

(d) None

Ans: (b)

1. Change of entropy is zero under a

(a) Isothermal process

(b) Isochoric process

(c) Isobaric process

(d) None

Ans: (d)

1. Change of entropy is zero during a

(b) Isenthalpic process

(c) Constant internal energy process

(d) None

Ans: (d)

1. Change of specific entropy during heating at constant volume process is

(a) Cp ln (p2/p1)

(b) Cv ln (p2/p1)

(c) Cp ln (T2/T1)

(d) None

Ans: (d)

1. Change of entropy during an isothermal process will be

(a) Cp ln (v2/v1)

(b) Cv ln (v2/v1)

(c) R ln (v2/v1)

(d) None

Ans: (c )

1. General expression for the change of entropy is

(a) R ln (v2/v1) + Cp ln(T2/T1)

(b) R ln (v2/v1) + Cv ln(T2/T1)

(c) Cp ln (v2/v1) + Cp ln(T2/T1)

(d) None

Ans: (b)

1. Change of entropy during an adiabatic process will be

(a) ((n—γ)/(n—1)) ln(T2/T1)

(b) Cp ((n—γ)/(n—1)) ln(T2/T1)

(c) Cv ((n—γ)/(n—1)) ln(T2/T1)

(d) None

Ans: (C)

1. Change of entropy during a reversible adiabatic process will be

(a) ((n—γ)/(n—1)) ln(T2/T1)

(b) Cp ((n—γ)/(n—1)) ln(T2/T1)

(c) Cv ((n—γ)/(n—1)) ln(T2/T1)

(d) None

Ans: (d)

1. During any irreversible process, there is

(a) Increase of entropy

(b) Decrease of entropy

(c) No change in entropy

(d) None

Ans: (a)

1. Increase of entropy is

(a) Good

(d) None

Ans: (c)

1. Decrease of entropy will be in case of

(a) Decrease in pressure

(b) Decrease in volume

(c) Both with decrease in pressure as well as volume

(d) None

Ans: (b)

1. Entropy increases with the

(b) Removal of heat

(c) At constant heat

(d) None

Ans:(a)

1. Entropy becomes double when

(a) Temperature is doubled

(b)Pressure is doubled

(c) Volume is doubled

(d) None

Ans: (d)

1. A Carnot cycle is a

(a) Real cycle

(b) Ideal cycle

(c) Experimentally verified cycle

(d) None

Ans: (b)

1. A Carnot cycle on a temperature entropy chart will be a

(a) Rhombus

(b) Rectangle

(c) Triangle

(d) None

Ans: (b)

1. The order of processes in a Carnot Cycle is

(a) Isothermal—isothermal—isentropic—isentropic

(b) Isothermal—isentropic—isentropic–—isothermal

(c) Isothermal—isentropic——isothermal –isentropic

(d) None

Ans: (c)

1. Over the complete Carnot Cycle, entropy

(a) increases

(b) Decreases

(c) No change

(d) None

Ans:(c )

1. With the rise of temperature in a system, sum of entropies of a system and its surroundings

(a) Increases

(b) Decreases

(c) Remains constant

(d) None

Ans: (c)

1. With the rise of pressure in a system, sum of entropies of a system and its surroundings

(a) Increases

(b) Decreases

(c) Remains constant

(d) None

Ans: (c)

1. A petrol heat engine assumed to work on Carnot Cycle between temperatures of 12000C and 2000 C. The efficiency of the engine will be

(a) 25.9 %

(b) 50. 9 %

(c) 67.9 %
(d)None

Ans: (c)

1. Work done will be maximum using pvn=Constant when the value of index ‘n’ will be

(a) 1

(b) 1.4

(c) 1.3

(d) None

Ans: (b)

1. Work done will be minimum using pvn=Constant when the value of index ‘n’ will be

(a) 1

(b) 1.4

(c) 1.3

(d) None

Ans: (a)

1. Compression ratio in a diesel cycle/petrol cycle is approximately equal to

(a) 1.5

(b) 2.5

(c) 3.5

(d) None

Ans: (b)