# Entropy - Mechanical Engineering (MCQ) questions and answers

1)   The degree of disorder of a mixture of two gases

a. is always less than the degrees of disorder of individual gases
b. is always greater than the degrees of disorder of individual gases
c. is always equals the degrees of disorder of individual gases
d. none of the above
 Answer  Explanation ANSWER: is always greater than the degrees of disorder of individual gases Explanation: No explanation is available for this question!

2)   Thermodynamics is the study of

a. energy
b. equilibrium
c. entropy
d. none of the above
 Answer  Explanation ANSWER: none of the above Explanation: No explanation is available for this question!

3)   The total energy of the universe

a. is always increasing
b. is always decreasing
c. either increases or decreases
d. is always constant
 Answer  Explanation ANSWER: is always constant Explanation: No explanation is available for this question!

4)   Carnot cycle contains two reversible adiabatic process and

a. two reversible isentropic processes
b. two reversible isobaric processes
c. two reversible isochoric processes
d. two reversible isothermal processes
 Answer  Explanation ANSWER: two reversible isothermal processes Explanation: No explanation is available for this question!

5)   What is the equation for entropy of a system if two parts 1 and 2 having entropies S1 and S2 are considered in equilibrium?

a. S = S1 – S2
b. S = S1 + S2
c. S = (S1 + S2) / 2
d. S = √S1 S2
 Answer  Explanation ANSWER: S = S1 + S2 Explanation: No explanation is available for this question!

6)   What is the entropy chosen at the triple point of water?

a. zero
b. less than zero
c. more than zero
d. none of the above
 Answer  Explanation ANSWER: zero Explanation: No explanation is available for this question!

7)   What is the reason behind the fact that the absolute zero entropy value is not attainable?

a. because absolute zero temperature is not attainable in finite number of operations
b. because theoretically absolute zero temperature has negative value of entropy and it is not possible
c. both a. and b.
d. none of the above
 Answer  Explanation ANSWER: because absolute zero temperature is not attainable in finite number of operations Explanation: No explanation is available for this question!

8)   At the state of perfect order (W = 1) of pure crystalline substance, how is the zero entropy defined?

a. entropy at 0 °C temperature
b. entropy at absolute zero temperature
c. entropy at the freezing point of the substance
d. none of the above
 Answer  Explanation ANSWER: entropy at absolute zero temperature Explanation: No explanation is available for this question!

9)   If the two parts A and B in a system are considered to be in equilibrium and having thermodynamic probabilities WA and WB, what will be the thermodynamic probability of the system?

a. W = WA . WB
b. W = WA + WB
c. W = (WA + WB) / 2
d. W = √(WA – WB)
 Answer  Explanation ANSWER: W = WA . WB Explanation: No explanation is available for this question!

10)   At the most probable state of a system the entropy of the system is

a. minimum
b. maximum
c. constant
d. none of the above
 Answer  Explanation ANSWER: maximum Explanation: No explanation is available for this question!

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