# Thermodynamics Questions and Answers – Reversibility, Irreversibilty and causes of Irreversibilty

This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Reversibility, Irreversibilty and causes of Irreversibilty”.

1. A reversible process is performed in such a way that
a) at the conclusion of process, both system and surroundings can be restored to their initial states without producing any change
b) it should not leave any trace to show that the process had ever occurred
c) it is carried out infinitely slowly
d) all of the mentioned

Explanation: These are some basic concepts of a reversible process.

2. A reversible process coincides with a quasi-static process.
a) true
b) false

Explanation: A reversible process is carried out very slowly and every state it passes through is an equilibrium state.

3. Irreversibility of a process may be due to
a) lack of equilibrium during the process
b) involvement of dissipative effects
c) both of the mentioned
d) none of the mentioned

Explanation: These two are the major causes of irreversibility.

4. A heat transfer process approaches reversibility as the temperature difference between two bodies approaches
a) infinity
b) zero
c) -1
d) 1

Explanation: For heat transfer to be reversible, heat must be transferred through an infinitesimal temperature difference.

5. All actual heat transfer processes are
a) irreversible
b) take place through a finite temperature difference
c) both of the mentioned
d) none of the mentioned

Explanation: An infinitesimal temperature difference is not easy to attain.
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6. Free expansion is irreversible.
a) true
b) false

Explanation: It can be demonstrated by the second law.

7. Which of the following can be a cause of irreversibility?
a) friction, viscosity
b) inelasticity
c) electrical resistance, magnetic hysteresis
d) all of the mentioned

Explanation: These effects are known as dissipative effects.

8. The continual motion of a movable device in the complete absence of friction is known as
a) PMM2
b) PMM3
c) PMM1
d) PMM0

Explanation: This is not possible since lubrication cannot be completely eliminated.

9. The friction present in moving devices makes a process reversible.
a) true
b) false

Explanation: Friction lakes the process irreversible.

10. Which of the following is irreversible?
a) stirring work
b) friction work in moving devices
c) current flowing through a wire
d) all of the mentioned

Explanation: All these processes includes a particular cause of irreversibility.

11. A process will be reversible if it has
a) no dissipative effects
b) dissipative effects
c) depends on the given conditions
d) none of the mentioned

Explanation: Without any dissipative effects, a process can perform in a reversible manner.

12. Irreversibility can be distinguished in how many types?
a) 0
b) 1
c) 2
d) 3

Explanation: Tow types of irreversibility are internal and external irreversibility.

13. Internal irreversibility is caused by
a) internal dissipative effects
b) friction, turbulence
c) electrical resistance, magnetic hysteresis
d) all of the mentioned

Explanation: Internal dissipative effects are the major cause of internal irreversibility.

14. The external irreversibility occurs at the system boundary.
a) true
b) false

Explanation: This mainly includes heat interaction with the surroundings due to a finite temperature gradient.

15. Which of the following is true?
a) mechanical irreversibility is due to finite pressure gradient
b) thermal irreversibility is due to finite temperature gradient
c) chemical irreversibility is due to finite concentration gradient
d) all of the mentioned

Explanation: These are some other distinctions of irreversibility.

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