This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Entropy Transfer Mechanisms”.
1. Entropy can be transferred to or from a system in which of the following forms?
a) heat transfer
b) mass flow
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: Entropy is transferred by these two forms while energy id transferred by work also.
2. Entropy transfer for an adiabatic transfer is zero.
a) true
b) false
View Answer
Explanation: The only form of entropy interaction associated with a fixed mass or closed system is heat transfer.
3. If heat Q flows reversibly from the system to the surroundings at To,
a) entropy increase of the surroundings is Q/To
b) entropy of the system is reduced by Q/To
c) system has lost entropy to the surroundings
d) all of the mentioned
View Answer
Explanation: We can say that there is entropy transfer from the system to the surroundings along with heat flow.
4. The sign of entropy transfer is opposite to the sign of heat transfer.
a) true
b) false
View Answer
Explanation: The sign of entropy transfer is same as the sign of heat transfer: positive, if into the system, and negative, if out of the system.
5. ____ is exchanged during work interaction, whereas both ____ and ____ are exchanged during heat transfer.
a) energy, energy and entropy
b) entropy, energy and entropy
c) mass, energy and entropy
d) none of the mentioned
View Answer
Explanation: This is the distinction between heat transfer and work which is brought about by the second law.
6. Mass contains
a) entropy
b) energy
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is a basic fact and the entropy and energy of a system are proportional to the mass.
7. The entropy of a system ____ by ____ when the mass of amount m enters it.
a) decreases, ms
b) increases, ms
c) decreases, s/m
d) increases, s/m
View Answer
Explanation: When mass m enters a system, an entropy of amount ms, s being the specific entropy, accompanies it.
8. What happens when heat is added to the system?
a) dQ is positive
b) dS=dQ/T
c) entropy of the system increases
d) all of the mentioned
View Answer
Explanation: dS=dQ/T and when heat is added, dQ=positive and thus dS=positive.
9. The first law of thermodynamics makes no distinction between heat transfer and work.
a) true
b) false
View Answer
Explanation: The first law of thermodynamics considers both work and heat transfer equal.
10. Which of the following explains that there is no entropy transfer associated with work.
a) working of flywheel
b) compression of spring
c) raising of weight by a certain height
d) all of the mentioned
View Answer
Explanation: In all these examples, there is work done but there is no entropy transfer.
Sanfoundry Global Education & Learning Series – Thermodynamics.
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