Free Practice Quiz Question List

4 The Second Law and Entropy Online Quiz Questions

Use this free practice quiz with 20 questions to review 4 The Second Law and Entropy, test your knowledge, and prepare for your next test or exam.

20 questions

Fill in the blank

1 point

An ideal process that can be reversed while leaving both the system and surroundings unchanged is called a process.

True or false

1 point

True or false: Because entropy is a state property, its change between fixed equilibrium states depends on the actual path taken.

A
True
B
False

Choose one

1 point

A refrigerator cools its interior while the room is warmer. Which statement explains how this is consistent with the second law?

A
Heat moves from the cold interior to the warmer room spontaneously, without any input.
B
Work supplied from outside allows heat to be moved from the cold interior to the warmer room.
C
Heat moves from cold to hot only if the refrigerator rejects no heat to its surroundings.
D
The refrigerator makes heat flow spontaneously from cold to hot by conserving energy.

True or false

1 point

True or false: A decrease in a system's entropy can be consistent with the second law if enough entropy is transferred to its surroundings.

A
True
B
False

Fill in the blank

1 point

An entropy change can be calculated along a reversible path even when the actual process connecting the same equilibrium states is .

Choose all

1 point

Select all the processes listed that are common causes of irreversibility.

A
Friction
B
Heat transfer across an infinitesimal temperature difference in an ideal reversible limit
C
Mixing
D
Unrestrained expansion
E
A reversible process with zero entropy generation

Choose one

1 point

A cyclic heat engine absorbs $1000\,\mathrm{J}$ and rejects $400\,\mathrm{J}$ to a cold reservoir. What is its thermal efficiency?

A
40%
B
50%
C
60%
D
140%

Choose all

1 point

Two heat engines operate between the same hot and cold reservoirs. Select all statements guaranteed by the second law.

A
A reversible engine achieves the maximum possible efficiency between the two reservoirs.
B
No real engine operating between the same reservoirs can be more efficient than a reversible engine.
C
Every real engine operating between the reservoirs reaches the Carnot efficiency.
D
The maximum efficiency depends on the working substance rather than the reservoir temperatures.

Written response

1 point

$120\,\mathrm{J}$ of heat flows from a $600\,\mathrm{K}$ body to a $300\,\mathrm{K}$ body. Treat each body's temperature as constant. What is the total entropy change of the two bodies? Enter your answer in J/K.

Written response

1 point

A reversible engine operates between reservoirs at $500\,\mathrm{K}$ and $300\,\mathrm{K}$ . What is its maximum possible efficiency? Enter your answer as a percentage value.

Choose one

1 point

A heat engine operates between reservoirs at $600\,\mathrm{K}$ and $300\,\mathrm{K}$ . An engineer claims the engine has an efficiency of 50%. Which assessment is correct?

A
It is impossible because the second law requires every engine to have efficiency below 50%.
B
It is possible only for an ideal reversible engine; a real engine must be less efficient.
C
It is possible for any real engine because energy is conserved.
D
It is possible only if the engine rejects no heat.

Open ended

1 point

Explain why a cyclic heat engine cannot convert all the heat it absorbs into work. Relate your explanation to the Carnot efficiency limit and clarify whether this limit means energy is destroyed.

Choose one

1 point

Which statement most accurately describes entropy in thermodynamics?

A
Entropy is exactly the same thing as visual disorder.
B
Entropy is a thermodynamic state property; “disorder” is only a rough analogy.
C
Entropy is energy that has been destroyed.
D
Entropy is defined only for reversible processes.

Choose one

1 point

Which statement expresses the Clausius version of the second law of thermodynamics?

A
Heat cannot flow from a hotter body to a colder body.
B
Heat does not flow spontaneously from a colder body to a hotter body.
C
A heat engine can convert all absorbed heat into work if it operates in a cycle.
D
A refrigerator moves heat from cold to hot without requiring external work.

True or false

1 point

For a reversible process, the entropy generated within the system is zero.

A
True
B
False

Choose one

1 point

A system undergoes a process in which its entropy decreases. Which condition is consistent with the entropy balance?

A
It generates a negative amount of entropy.
B
The second law forbids any decrease in the entropy of a system.
C
It transfers enough entropy to its surroundings to outweigh the entropy generated within it.
D
Its temperature must remain constant throughout the process.

Choose one

1 point

An irreversible process takes a system between two equilibrium states. How can its entropy change be calculated?

A
Calculate the entropy change along any reversible path connecting the same equilibrium states.
B
Calculate the entropy change only along the actual path, which must be reversible.
C
Use the entropy generated alone as the system’s entropy change.
D
Assume the entropy change is zero because entropy is a state property.

Choose one

1 point

Which process necessarily involves positive entropy generation?

A
An ideal reversible process generates a positive amount of entropy.
B
Entropy generation is negative whenever heat leaves a system.
C
Heat transfer across a finite temperature difference generates entropy.
D
Entropy generation depends only on whether the system’s entropy increases.

Written response

1 point

A quantity of $120\ \mathrm{J}$ of heat flows from an object at $400\ \mathrm{K}$ to one at $300\ \mathrm{K}$ . What is the total entropy change of the two objects? Enter the numerical value in J/K.

Written response

1 point

A heat engine operates between reservoirs at $T_H=500\ \mathrm{K}$ and $T_C=300\ \mathrm{K}$ . What is its maximum possible efficiency? Enter the percentage value.