Applications of Second Law in Thermodynamics for BEng Students

Question 1

Which of the following is NOT an application of the Second Law of Thermodynamics in the field of engineering?

Accepted Answer

Nuclear fusion

Answer

Power generation

Answer

Refrigeration

Answer

Fuel cell design

Question 2

According to the Second Law, which of the following processes is inherently irreversible?

Accepted Answer

Heat transfer from a higher temperature reservoir to a lower temperature reservoir

Answer

Adiabatic expansion of an ideal gas

Answer

Isothermal compression of an ideal gas

Answer

Adiabatic compression of an ideal gas

Question 3

Which of the following statements about the entropy change of a closed system undergoing an irreversible process is true?

Accepted Answer

Entropy increases

Answer

Entropy decreases

Answer

Entropy remains constant

Answer

Entropy may increase or decrease

Question 4

Which of the following is a common type of refrigeration system that utilizes the principles of the Second Law of Thermodynamics?

Accepted Answer

Vapour compression system

Answer

Stirling engine

Answer

Peltier cooler

Answer

Thermoelectric generator

Question 5

Consider a reversible heat engine operating between two reservoirs at temperatures T1 and T2. If the engine absorbs heat Q1 from the high-temperature reservoir, what is the work output of the engine?

Accepted Answer

Q1 - Q2

Answer

Q1

Answer

Q2

Answer

Q2 - Q1

Question 6

Which of the following is a measure of the disorder or randomness of a system at the microscopic level?

Accepted Answer

Entropy

Answer

Enthalpy

Answer

Exergy

Answer

Internal energy

Question 7

Consider a closed system undergoing an adiabatic process. What happens to the entropy of the system?

Accepted Answer

Entropy remains constant

Answer

Entropy increases

Answer

Entropy decreases

Answer

Entropy may increase or decrease

Question 8

Which of the following consequences is NOT derived from the Second Law of Thermodynamics?

Accepted Answer

Heat engines can convert all heat input into work

Answer

Heat naturally flows from regions of higher temperature to regions of lower temperature

Answer

The entropy of an isolated system increases over time

Answer

Absolute zero temperature is impossible to achieve

Question 9

A refrigerator maintains a temperature of 4°C inside while the surrounding environment is at 25°C. What is the theoretical minimum Coefficient of Performance (COP) of this refrigerator?

Accepted Answer

2.63

Answer

3.13

Answer

4.25

Answer

5.00

Question 10

Which statement accurately describes Carnot's theorem?

Accepted Answer

All reversible heat engines operating between the same two reservoirs will have the same efficiency

Answer

Irreversible heat engines can be more efficient than reversible heat engines operating between the same two reservoirs

Answer

Carnot's theorem is only applicable to ideal heat engines

Answer

Carnot's efficiency is always greater than 50%

Question 11

In a Rankine cycle, which process releases heat to the environment?

Accepted Answer

Condensation

Answer

Evaporation

Answer

Compression

Answer

Expansion

Question 12

For an irreversible process, the entropy generation rate is:

Accepted Answer

Positive

Answer

Zero

Answer

Negative

Answer

Cannot be determined

Question 13

According to the Clausius inequality, the entropy of an isolated system:

Accepted Answer

Increases

Answer

Decreases

Answer

Remains constant

Answer

Fluctuates randomly

Question 14

Which of the following is a valid interpretation of entropy?

Accepted Answer

A measure of the disorder of a system

Answer

A measure of the lost energy of a system

Answer

A measure of the heat transfer between a system and its surroundings

Answer

A measure of the work done by a system

Question 15

In a reversible heat engine, the ratio of the work done per cycle to the heat absorbed from the reservoir is:

Accepted Answer

Equal to 1.

Answer

Greater than 1.

Answer

Less than 1.

Answer

Zero.

Question 16

Which of the following is NOT an application of the Second Law in power generation?

Accepted Answer

Refrigerator

Answer

Gas turbine

Answer

Steam turbine

Answer

Combined cycle power plant

Question 17

Which of the following is NOT a thermodynamic property?

Accepted Answer

Velocity

Answer

Temperature

Answer

Density

Answer

Pressure

Question 18

The exergy of a system is a measure of:

Accepted Answer

The potential useful work that can be extracted from the system.

Answer

The minimum work required to create the system.

Answer

The entropy of the system.

Answer

The temperature of the system.

Question 19

Which process is not considered reversible?

Accepted Answer

Combustion of fuel

Answer

Adiabatic expansion of an ideal gas

Answer

Isothermal compression of an ideal gas

Answer

Condensation of a pure substance at its boiling point

Question 20

Which of the following is NOT an application of the Second Law of Thermodynamics?

Accepted Answer

Creating perpetual motion machines.

Answer

Predicting the direction of spontaneous processes.

Answer

Calculating the efficiency of heat engines.

Answer

Designing refrigeration systems.

Question 21

According to Clausius' statement of the Second Law of Thermodynamics, which is not possible?

Accepted Answer

Creating a perpetual motion machine that produces work without an energy input

Answer

Heat transfer from cold to hot bodies

Answer

Increasing entropy in an isolated system

Answer

Violation of energy conservation

Question 22

Which device transfers heat from a cold reservoir to a hot reservoir?

Accepted Answer

Refrigerator

Answer

Air conditioner

Answer

Car engine

Answer

Solar panel

Question 23

What primarily limits the efficiency of heat engines?

Accepted Answer

Irreversibilities

Answer

Friction

Answer

Heat loss

Answer

Material limitations

Question 24

How is entropy related to disorder?

Accepted Answer

Entropy quantifies the level of disorder in a system.

Answer

Disorder quantifies the entropy of a system.

Answer

Entropy and disorder are unrelated.

Answer

Entropy is the opposite of disorder.

Question 25

Which statement is NOT a consequence of the Second Law of Thermodynamics?

Accepted Answer

All reversible processes have an efficiency of 100%.

Answer

Heat cannot spontaneously flow from a cold reservoir to a hot reservoir.

Answer

The total entropy of an isolated system can only increase or remain constant, never decrease.

Answer

No heat engine can operate with 100% efficiency.

Question 26

A refrigerator is a device that utilizes the reversed Carnot cycle to remove heat from a cold reservoir and transfer it to a hot reservoir.

Accepted Answer

True

Answer

False

Question 27

Which of the following factors does NOT affect the efficiency of a heat pump?

Accepted Answer

Size of the evaporator

Answer

Temperature difference between the heat source and sink

Answer

Type of refrigerant used

Answer

Pressure ratio of the compressor

Question 28

Entropy is a measure of the degree of disorder or randomness in a system.

Accepted Answer

True

Answer

False

Question 29

Which of the following statements correctly describes the Second Law of Thermodynamics?

Accepted Answer

Heat flows from hot to cold, and entropy always increases in a closed system.

Answer

Energy can be created or destroyed.

Answer

Entropy always decreases in an isolated system.

Answer

Processes are always reversible.

Question 30

In a power plant, the efficiency is ultimately limited by:

Accepted Answer

The Carnot efficiency.

Answer

The available energy in the fuel.

Answer

The Brayton cycle efficiency.

Answer

The Rankine cycle efficiency.

Question 31

Which of the following processes is irreversible?

Accepted Answer

Friction

Answer

Isochoric heating of an ideal gas

Answer

Adiabatic compression of an ideal gas

Answer

Isothermal expansion of an ideal gas

Question 32

Entropy can be defined as:

Accepted Answer

A measure of the disorder of a system.

Answer

A measure of the efficiency of a process.

Answer

The amount of heat energy in a system

Answer

A conserved quantity in all processes.

Question 33

In a refrigeration system, the coefficient of performance (COP) is the ratio of:

Accepted Answer

Cooling capacity to power input.

Answer

Power input to cooling capacity.

Answer

Cooling capacity to heat rejected.

Answer

Heat rejected to cooling capacity.

Question 34

The Second Law of Thermodynamics can be used to determine:

Accepted Answer

The direction of spontaneous processes.

Answer

The rate of heat transfer.

Answer

The exact values of thermodynamic properties.

Answer

The fluid flow patterns in a system.

Question 35

The Carnot efficiency is:

Accepted Answer

The maximum possible efficiency of a heat engine operating between two reservoirs at different temperatures.

Answer

The efficiency of a Rankine cycle power plant.

Answer

The efficiency of an ideal refrigerator.

Question 36

Which of the following is NOT an implication of the Second Law of Thermodynamics?

Accepted Answer

Energy can be created without destroying an equal amount of energy.

Answer

Natural processes tend to progress towards a state of increased disorder.

Answer

Perpetual motion machines of the second kind are impossible to create.

Answer

The efficiency of a heat engine can never reach 100%.

Question 37

In a throttling process, which thermodynamic property remains unchanged?

Accepted Answer

Enthalpy

Answer

Pressure

Answer

Temperature

Answer

Entropy

Question 38

What is the primary purpose of a diffuser in a jet engine?

Accepted Answer

To reduce the velocity and increase the pressure of the incoming air.

Answer

To increase the velocity and reduce the pressure of the incoming air.

Answer

To combust fuel and produce thrust.

Question 39

For an irreversible process between two defined end states, the entropy change of the system is always ______ compared to that of a reversible process between the same end states.

Accepted Answer

Greater

Answer

Unpredictable

Answer

Less

Answer

Equal

Question 40

Which statement about exergy is incorrect?

Accepted Answer

Exergy is conserved in a closed system, regardless of internal changes.

Answer

Exergy analysis can be applied to enhance the efficiency of engineering systems.

Answer

Exergy represents the maximum obtainable useful work from a system as it reaches equilibrium with its environment.

Answer

Exergy destruction is an indicator of irreversibility in a process.

Question 41

The availability of a system at a certain state is defined as the _______ work that can be extracted from the system as it reaches equilibrium with its surroundings.

Accepted Answer

Maximum

Answer

Average

Answer

Minimum