Thermodynamics for Engineering Mechanics: Online Learning Quizzes

Question 1

Which of the following statements contradicts a fundamental law of thermodynamics?

Accepted Answer

Heat can spontaneously flow from a colder region to a hotter region.

Answer

The total energy of an isolated system remains constant.

Answer

The entropy of an isolated system can never decrease.

Answer

No heat engine can be 100% efficient.

Question 2

According to the First Law of Thermodynamics, which statement is accurate?

Accepted Answer

The First Law of Thermodynamics applies to energy transfers in all systems.

Answer

Energy can be created or destroyed.

Answer

The First Law of Thermodynamics is used to calculate the efficiency of heat engines.

Answer

The First Law of Thermodynamics is only applicable to closed systems.

Question 3

In a closed system undergoing a reversible process, what happens to the system's entropy?

Accepted Answer

It stays the same.

Answer

It goes down.

Answer

It goes up.

Question 4

In a closed system, a reversible process is one in which the entropy of the system:

Accepted Answer

Remains constant

Answer

Increases

Answer

Decreases

Answer

Increases in the surroundings

Question 5

According to the First Law of Thermodynamics, what is the relationship between the change in internal energy of a system, the heat added to the system, and the work done by the system?

Accepted Answer

The change in internal energy is equal to the heat added minus the work done.

Answer

Energy can be created or destroyed.

Answer

The entropy of an isolated system always increases.

Answer

Heat always flows from a cold reservoir to a hot reservoir.

Question 6

Which statement accurately reflects the Second Law of Thermodynamics?

Accepted Answer

Irreversibility is inherent in all real-world processes.

Answer

Entropy always decreases in isolated systems.

Answer

Heat can flow spontaneously from cold to hot objects.

Answer

The Second Law is simply a restatement of the First Law of Thermodynamics.

Question 7

According to the First Law of Thermodynamics, which statement is accurate?

Accepted Answer

The change in internal energy of a closed system equals the heat added to the system minus the work done by the system.

Answer

Energy can be created or destroyed.

Answer

A heat engine can have an efficiency greater than 100%.

Question 8

According to the Second Law of Thermodynamics, which statement accurately describes the efficiency of heat engines?

Accepted Answer

Real heat engines always have an efficiency less than 100%.

Answer

Ideal heat engines can achieve 100% efficiency.

Answer

Heat engine efficiency depends solely on the temperature difference between reservoirs.

Answer

The Second Law of Thermodynamics does not limit heat engine efficiency.

Question 9

According to the Second Law of Thermodynamics, which of the following statements is true?

Accepted Answer

The entropy of an isolated system always increases over time.

Accepted Answer

No heat engine can be perfectly efficient.

Answer

Heat can flow spontaneously from a colder to a warmer body.

Question 10

Which statement best describes the Second Law of Thermodynamics?

Accepted Answer

No process can be perfectly efficient, as some energy is always lost as heat or due to irreversibilities.

Answer

Heat can flow spontaneously from a colder reservoir to a hotter one.

Answer

The entropy of an isolated system always decreases over time.

Answer

The Third Law of Thermodynamics states that the entropy of a perfect crystal at absolute zero is non-zero.

Question 11

Which of the following is NOT considered a thermodynamic system?

Accepted Answer

A vacuum inside a flask

Answer

A sealed container filled with gas

Answer

A piston moving inside a cylinder

Answer

A mixture of water and ice in an insulated container

Question 12

The first law of thermodynamics states that:

Accepted Answer

Energy can neither be created nor destroyed, only transferred or transformed

Answer

Heat always flows from hot to cold

Answer

Entropy always increases over time

Answer

The total amount of work done on a system is equal to the change in its internal energy

Question 13

An isentropic process is one in which:

Accepted Answer

There is no change in entropy

Answer

There is no heat transfer

Answer

The temperature remains constant

Answer

The pressure remains constant

Question 14

The entropy of an isolated system:

Accepted Answer

Remains constant

Answer

Increases over time

Answer

Decreases over time

Answer

Can be either increasing or decreasing

Question 15

A reversible process is one that:

Accepted Answer

Can be reversed without any change in the system or its surroundings

Answer

Always involves heat transfer

Answer

Always involves friction

Answer

Is always spontaneous

Question 16

The efficiency of a Carnot engine operating between two reservoirs at temperatures T1 and T2 is given by:

Accepted Answer

T1 / (T1 - T2)

Answer

(T1 - T2) / T1

Answer

T2 / (T1 - T2)

Answer

T1 / T2

Question 17

Which of the following is NOT a thermodynamic property?

Accepted Answer

Mass

Answer

Temperature

Answer

Pressure

Answer

Volume

Question 18

The ideal gas law, PV = nRT, is valid for:

Accepted Answer

Ideal gases at low pressures and high temperatures

Answer

All gases under all conditions

Answer

Real gases at high pressures and low temperatures

Answer

Only monoatomic ideal gases

Question 19

The Joule-Thomson coefficient is defined as:

Accepted Answer

The ratio of the change in temperature to the change in pressure for an isenthalpic process

Answer

The ratio of the change in pressure to the change in temperature for an isobaric process

Answer

The ratio of the change in volume to the change in temperature for an adiabatic process

Answer

The ratio of the change in internal energy to the change in entropy for an isothermal process

Question 20

Define the first law of thermodynamics.

Accepted Answer

Energy can neither be created nor destroyed, only transferred or transformed.

Answer

Entropy always increases in an isolated system.

Answer

The total energy of an isolated system remains constant.

Answer

Heat cannot flow spontaneously from a colder to a hotter body.

Question 21

What is the change in entropy for an ideal gas undergoing an adiabatic process?

Accepted Answer

Zero

Answer

Greater than zero

Answer

Less than zero

Answer

Cannot be determined without additional information

Question 22

Which of the following processes involves constant pressure?

Accepted Answer

Constant pressure

Answer

Constant volume

Answer

Constant temperature

Answer

Constant entropy

Question 23

Explain the relationship between enthalpy and internal energy.

Accepted Answer

Enthalpy is equal to internal energy plus the product of pressure and volume.

Answer

Enthalpy is equal to internal energy.

Answer

Enthalpy is equal to internal energy minus the product of pressure and volume.

Answer

Enthalpy and internal energy are not related.

Question 24

Which property is NOT a defining characteristic of a thermodynamic system?

Accepted Answer

Momentum

Answer

Temperature

Answer

Pressure

Answer

Volume

Question 25

The first law of thermodynamics expresses the principle of:

Accepted Answer

Energy conservation

Answer

Entropy maximization

Answer

Heat irreversibility

Answer

Work equivalence

Question 26

Which process maintains constant temperature?

Accepted Answer

Isothermal compression

Answer

Isochoric heating

Answer

Isobaric cooling

Answer

Adiabatic expansion

Question 27

According to the second law of thermodynamics, the entropy of an isolated system tends to:

Accepted Answer

Increase

Answer

Remain constant

Answer

Decrease

Answer

Fluctuate randomly

Question 28

Which process is considered reversible?

Accepted Answer

Frictionless motion of a piston

Answer

Heat transfer through a perfect insulator

Answer

Spontaneous chemical reaction

Answer

Adiabatic compression of an ideal gas

Question 29

The efficiency of a heat engine is defined as the ratio of:

Accepted Answer

Work output to heat input

Answer

Heat input to work output

Answer

Heat output to heat input

Answer

Work output to heat output

Question 30

Which gas has the highest molar specific heat capacity at constant volume?

Accepted Answer

Hydrogen

Answer

Helium

Answer

Nitrogen

Answer

Oxygen

Question 31

In an isothermal reversible process, the change in entropy is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Indeterminate

Question 32

Which of the following is not a fundamental property of a thermodynamic system?

Accepted Answer

Density

Answer

Temperature

Answer

Pressure

Answer

Entropy

Question 33

According to the first law of thermodynamics, the total energy of an isolated system remains:

Accepted Answer

Constant

Answer

Increasing

Answer

Decreasing

Answer

Variable

Question 34

Entropy measures the:

Accepted Answer

Disorder of a system

Answer

Order of a system

Answer

Energy of a system

Answer

Temperature of a system

Question 35

An isothermal expansion of a gas is a:

Accepted Answer

Reversible process

Answer

Irreversible process

Answer

Adiabatic process

Answer

Isobaric process

Question 36

The efficiency of a heat engine is ultimately determined by:

Accepted Answer

Temperature difference between the hot and cold reservoirs

Answer

Work done by the engine

Answer

Heat added to the engine

Answer

Entropy change of the engine

Question 37

An isothermal process is one in which:

Accepted Answer

Temperature remains constant

Answer

Pressure remains constant

Answer

Volume remains constant

Answer

Entropy remains constant

Question 38

An adiabatic process is one in which:

Accepted Answer

No heat is transferred to or from the system

Answer

The system is in thermal equilibrium with its surroundings

Answer

The system is isolated from its surroundings

Answer

The entropy of the system decreases

Question 39

The first law of thermodynamics expresses the principle of:

Accepted Answer

Energy conservation

Answer

Entropy conservation

Answer

Reversibility of processes

Answer

Irreversibility of processes

Question 40

During an isothermal process, which quantity remains constant?

Accepted Answer

Temperature

Answer

Pressure

Answer

Volume

Answer

Entropy

Question 41

The second law of thermodynamics:

Accepted Answer

Predicts the directionality of natural processes

Answer

Introduces the concept of entropy

Answer

Relates heat transfer to work

Answer

Defines the ideal gas constant

Question 42

Entropy of a system:

Accepted Answer

Measures its level of disorder

Answer

Always increases

Answer

Always decreases

Answer

Is independent of temperature

Question 43

The Gibbs free energy represents:

Accepted Answer

Maximum useful work obtainable from a system

Answer

Total energy of a system

Answer

Entropy of a system

Answer

Heat capacity of a system

Question 44

Efficiency of a heat engine denotes:

Accepted Answer

Ratio of work output to heat input

Answer

Ratio of heat input to work output

Answer

Difference between heat input and work output

Answer

Sum of heat input and work output

Question 45

Which is NOT a type of thermodynamic system?

Accepted Answer

Adiabatic system

Answer

Open system

Answer

Closed system

Answer

Isolated system

Question 46

Which of the following is NOT a thermodynamic property?

Accepted Answer

Acceleration

Answer

Temperature

Answer

Entropy

Answer

Pressure

Question 47

The first law of thermodynamics states that:

Accepted Answer

Energy is conserved within a closed system.

Answer

Entropy decreases over time.

Answer

Heat cannot be converted into work.

Answer

The universe is contracting.

Question 48

Which of the following processes is isentropic?

Accepted Answer

Adiabatic reversible expansion

Answer

Isothermal irreversible compression

Answer

Polytropic irreversible process

Answer

Irreversible heat transfer

Question 49

Which of the following is a criterion for a heat engine to operate?

Accepted Answer

It must have a source of heat at a higher temperature than the sink.

Answer

It must operate on a single closed cycle.

Answer

It must convert all heat into work.

Answer

It must be reversible.

Question 50

The thermal efficiency of a heat engine operating on an ideal cycle is:

Accepted Answer

The ratio of the net work done by the engine to the heat added to the engine.

Answer

The ratio of the heat added to the engine to the net work done by the engine.

Answer

The ratio of the temperature of the heat source to the temperature of the heat sink.

Answer

Independent of the type of working fluid used in the engine.

Question 51

The specific heat of a substance is defined as:

Accepted Answer

The amount of heat required to raise the temperature of 1 unit mass of the substance by 1 unit of temperature.

Answer

The amount of heat required to raise the temperature of 1 mole of the substance by 1 unit of temperature.

Answer

The ratio of the heat capacity of the substance to its volume.

Answer

Independent of the pressure of the substance.

Question 52

Entropy can be interpreted as a measure of:

Accepted Answer

Disorder

Answer

Energy

Answer

Volume

Answer

Temperature

Question 53

Question: A closed thermodynamic system undergoes a reversible cycle. Why is the change in internal energy of the system over the complete cycle zero?

Accepted Answer

A. In a reversible cycle, the system returns to its initial state, so the net change in internal energy is zero.

Answer

B. The change in internal energy is always zero for any closed system.

Answer

C. In a reversible cycle, the work done by the system is equal to the change in internal energy.

Question 54

Which of the following is **not** a fundamental property of a closed thermodynamic system?

Accepted Answer

Mass

Answer

Pressure

Answer

Volume

Answer

Temperature

Question 55

Which of the following processes is **not** reversible?

Accepted Answer

Dissipation of heat through friction

Answer

Adiabatic compression of an ideal gas

Answer

Isothermal expansion of an ideal gas

Answer

Melting of ice at its melting point

Question 56

During an isothermal process of an ideal gas, the change in entropy is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Cannot be determined without more information

Question 57

A Carnot cycle consists of:

Accepted Answer

Two isothermal and two adiabatic processes

Answer

Two adiabatic and two isobaric processes

Answer

Two isochoric and two isobaric processes

Answer

Two isothermal and two isentropic processes

Question 58

Which of the following is NOT a type of thermodynamic system?

Accepted Answer

Adiabatic

Answer

Open

Answer

Closed

Answer

Isolated

Question 59

The SI unit of entropy is:

Accepted Answer

Joule per Kelvin

Answer

Watt per Kelvin

Answer

Pascal per Kelvin

Answer

Kelvin per Joule

Question 60

The first law of thermodynamics states that:

Accepted Answer

Energy can be transferred or transformed, but not created or destroyed.

Answer

Energy can be created or destroyed.

Answer

Entropy increases in all irreversible processes.

Answer

The efficiency of a heat engine cannot exceed 100%.

Question 61

Entropy measures:

Accepted Answer

The randomness or disorder of a system.

Answer

The constant heat added to a system divided by its temperature.

Answer

A property that can only be measured experimentally.

Answer

The change in internal energy of a system.

Question 62

The most efficient heat engine operating between two given reservoirs is the:

Accepted Answer

Carnot heat engine

Answer

Rankine cycle

Answer

Otto cycle

Answer

Diesel cycle

Question 63

The entropy change of a closed system in an irreversible process is:

Accepted Answer

Positive

Answer

Zero

Answer

Negative

Answer

Unpredictable

Question 64

Gibbs free energy represents:

Accepted Answer

The maximum work extractable from a system.

Answer

The minimum work required to create a system.

Answer

The change in internal energy of a system.

Answer

The change in entropy of a system.