# Thermodynamics Questions and Answers – Entropy Principle and its Applications-1

This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Entropy Principle and its Applications”.

1. Which of the following is true?
a) for an isolated system, dS>=0
b) for a reversible process, dS=0
c) for an irreversible process, dS>0
d) all of the mentioned

Explanation: For an isolated system which does not undergo any energy interaction with the surroundings, dQ=0 and also dS>=dQ/T.

2. The entropy of an isolated system can never ____
a) increase
b) decrease
c) be zero
d) none of the mentioned

Explanation: The entropy of an isolated system always increases and remains constant only when the process is reversible.

3. According to entropy principle, the entropy of an isolated system can never decrease and remains constant only when the process is reversible.
a) true
b) false

Explanation: This is the statement for the principle of increase of entropy.

4. Entropy may decrease locally at some region within the isolated system. How can this statement be justified?
a) this cannot be possible
b) this is possible because entropy of an isolated system can decrease.
c) it must be compensated by a greater increase of entropy somewhere within the system.
d) none of the mentioned

Explanation: The net effect of an irreversible process is an entropy increase of the whole system.

5. Clausius summarized the first and second laws of thermodynamics as
a) the energy of the world is constant
b) the entropy of the world tends towards a maximum
c) both of the mentioned
d) none of the mentioned

Explanation: These two statements were given by Clausius.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. The entropy of an isolated system always ____ and becomes a ____ at the state of equilibrium.
a) decreases, minimum
b) increases, maximum
c) increases, minimum
d) decreases, maximum

Explanation: If entropy of an isolated system varies with some parameter, then there is a certain value of that parameter which maximizes the entropy.

7. Entropy principle is the quantitative statement of the second law of thermodynamics.
a) true
b) false

Explanation: This is a general fact about entropy principle.

8. Which of the following can be considered as an application of entropy principle?
a) transfer of heat through a finite temperature difference
b) mixing of two fluids
c) maximum temperature obtainable from two finite bodies
d) all of the mentioned

Explanation: These are some basic applications of entropy principle.

9. The final temperatures of two bodies, initially at T1 and T2 can range from
a) (T1-T2)/2 to sqrt(T1*T2)
b) (T1+T2)/2 to sqrt(T1*T2)
c) (T1+T2)/2 to (T1*T2)
d) (T1-T2)/2 to (T1*T2)

Explanation: (T1+T2)/2 is the temperature when there is no delivery of work and sqrt(T1*T2) is the temperature with maximum delivery of work.

10. Which of the following processes exhibit external mechanical irreversibility?
a) isothermal dissipation of work
c) both of the mentioned
d) none of the mentioned

Explanation: These processes exhibit external mechanical irreversibility.

Sanfoundry Global Education & Learning Series – Thermodynamics.
To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]