Introduction to Thermodynamics: Master the Basics of Energy Transfer and Conversion

Question 1

Which fundamental property remains constant during all physical processes, according to the first law of thermodynamics?

Accepted Answer

Energy

Answer

Mass

Answer

Momentum

Answer

Entropy

Question 2

Which of the following is a key implication of the second law of thermodynamics?

Accepted Answer

Entropy of an isolated system never decreases.

Answer

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

Answer

Heat engines can operate with 100% efficiency.

Answer

Entropy measures the energy content of a system.

Question 3

An ideal gas undergoes an isothermal process from state 1 to state 2. What happens to the entropy of the gas?

Accepted Answer

It remains constant.

Answer

It increases.

Answer

It decreases.

Answer

It depends on the path taken.

Question 4

Which process is irreversible according to the second law of thermodynamics?

Accepted Answer

Adiabatic compression of a gas

Answer

Isothermal expansion of an ideal gas

Answer

Isobaric heating of a liquid

Answer

Isochoric cooling of a gas

Question 5

In a closed system undergoing a reversible process, what is the entropy change of the system?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Depends on the path taken

Question 6

Which of the following characterizes an isolated thermodynamic system?

Accepted Answer

Cannot exchange heat or work with surroundings

Answer

Can exchange heat with surroundings

Answer

Can perform work on surroundings

Answer

Can exchange mass with surroundings

Question 7

According to the second law of thermodynamics, which statement is true?

Accepted Answer

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

Answer

The entropy of an isolated system decreases over time.

Answer

All processes are perfectly efficient.

Answer

The change in entropy of a system is always positive.

Question 8

Which of the following is NOT considered a thermodynamic system?

Accepted Answer

The universe

Answer

Closed system

Answer

Open system

Answer

Isolated system

Question 9

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

Accepted Answer

Systems in thermal equilibrium with each other are also in thermal equilibrium with a third system.

Answer

Systems in thermal equilibrium with a third system must have different temperatures.

Answer

The Zeroth Law can be used to derive the First Law of Thermodynamics.

Answer

The Zeroth Law applies only to systems with constant volume.

Question 10

Which statement accurately describes the zeroth law of thermodynamics?

Accepted Answer

If system A is in thermal equilibrium with system B, and system B is in thermal equilibrium with system C, then system A is in thermal equilibrium with system C.

Answer

Heat always flows from higher temperature regions to lower temperature regions.

Answer

The entropy of an isolated system always increases over time.

Answer

The internal energy of a system is a function of its temperature and volume.

Question 11

Which statement accurately describes the second law of thermodynamics?

Accepted Answer

Heat naturally flows from a hotter object to a colder object.

Answer

Entropy always decreases in an isolated system.

Answer

All processes are perfectly efficient.

Answer

The universe is becoming increasingly ordered.

Question 12

According to the zeroth law of thermodynamics, which of the following is true?

Accepted Answer

Systems in thermal equilibrium with each other are also in thermal equilibrium with a third system.

Answer

Temperature is a subjective feeling that varies from person to person.

Answer

Heat always flows from objects with higher temperatures to objects with lower temperatures.

Answer

The zeroth law applies exclusively to ideal gases.

Question 13

In an isothermal process applied to a closed system, what occurs?

Accepted Answer

Heat exchange equals work done.

Answer

Internal energy changes.

Answer

Entropy decreases.

Answer

Phase transition occurs.

Question 14

A closed system undergoes a process where heat is transferred into it, but no work is done on it. What happens to the system's internal energy?

Accepted Answer

Increases

Answer

Decreases

Answer

Stays the same

Answer

Cannot be determined without knowing the system's specific heat capacity

Question 15

According to the first law of thermodynamics, what happens to the total energy of an isolated system?

Accepted Answer

It remains constant.

Answer

It can be created or destroyed.

Answer

It always decreases.

Answer

It always increases.

Question 16

According to the second law of thermodynamics, what happens to the total energy of a closed system?

Accepted Answer

Remains constant

Answer

Decreases over time

Answer

Can flow spontaneously from a colder to a hotter region

Answer

Can reach 100% efficiency for a heat engine operating within the system

Question 17

According to the zeroth law of thermodynamics, what is the essential condition for two systems to be in thermal equilibrium?

Accepted Answer

Equal temperature

Answer

Heat exchange

Answer

Equal volume

Answer

Identical material composition

Question 18

In a closed system, heat is added and work is done by the system. Based on the first law of thermodynamics, what is the change in internal energy, ΔU, of the system?

Accepted Answer

ΔU = Q - W

Answer

ΔU = W - Q

Answer

ΔU = Q + W

Question 19

Which of the following best describes the first law of thermodynamics?

Accepted Answer

A restatement of the law of conservation of energy

Answer

A method for calculating heat engine efficiency

Answer

Applicable only to closed systems

Answer

A violation of the law of conservation of energy

Question 20

During an isothermal process involving an ideal gas, which property remains unchanged?

Accepted Answer

Temperature

Answer

Volume

Answer

Pressure

Question 21

In a closed system, the entropy always increases over time, irrespective of heat transfer. Which law of thermodynamics does this observation demonstrate?

Accepted Answer

Second Law of Thermodynamics

Answer

Zeroth Law of Thermodynamics

Answer

First Law of Thermodynamics

Answer

Third Law of Thermodynamics

Question 22

Which of the following is **not** a characteristic of the first law of thermodynamics?

Accepted Answer

Applies to isolated systems only

Answer

Describes the conservation of energy

Answer

Relates heat and work to the change in internal energy

Answer

Mathematical representation is ΔU = Q - W

Question 23

In thermodynamics, which system can exchange energy, but not mass, with its surroundings?

Accepted Answer

Closed system

Answer

Open system

Answer

Isolated system

Question 24

In accordance with the second law of thermodynamics, which process type results in an increase in the entropy of a system?

Accepted Answer

Irreversible

Answer

Isothermal

Answer

Reversible

Answer

Adiabatic

Question 25

In a heat engine, efficiency measures the engine's ability to convert heat into useful work. Why is efficiency important in a heat engine?

Accepted Answer

It determines the engine's ability to convert heat into useful work, with higher efficiency meaning less heat is wasted.

Answer

It indicates the amount of heat lost to the environment.

Answer

It represents the maximum amount of work obtainable from the heat input.

Answer

It is solely determined by the temperature of the hot reservoir.

Question 26

According to the zeroth law of thermodynamics, what condition indicates thermal equilibrium between two systems?

Accepted Answer

Equal temperatures

Answer

Equal heat transfer

Answer

Equal internal energies

Question 27

In an adiabatic and closed system undergoing a process, can heat be transferred from the system to the surroundings? Explain your answer.

Accepted Answer

No, heat cannot be transferred from the system to the surroundings.

Answer

Yes, heat can be transferred from the system to the surroundings.

Answer

Yes, but only if the system is also undergoing isothermal compression.

Answer

No, but only if the system is at a constant volume.

Question 28

Define the specific enthalpy, 'h'.

Accepted Answer

h = u + pV

Answer

h = u - pV

Answer

h = PV

Question 29

In thermodynamics, availability represents:

Accepted Answer

The maximum work obtainable from a system undergoing a reversible process.

Answer

The difference between actual and ideal work in a process.

Answer

The heat transferred to or from the system.

Answer

The change in the system's internal energy.

Question 30

In evaluating energy conversion systems, why is exergy important? How do inefficiencies and irreversibilities affect exergy destruction? Suggest strategies to reduce exergy losses in these systems.

Accepted Answer

Exergy represents the maximum theoretical work obtainable from a system or energy source.

Accepted Answer

Strategies to minimize exergy losses include using energy-efficient technologies and optimizing system design.

Answer

Irreversibilities in energy conversion systems do not impact exergy destruction.

Answer

Exergy destruction is always beneficial as it improves the efficiency of energy conversion systems.

Question 31

According to the second law of thermodynamics, what limits the maximum efficiency of a heat engine, and what factors influence its performance?

Accepted Answer

The Carnot efficiency, which depends on the temperature difference between the reservoirs.

Answer

The first law of thermodynamics, which prevents the complete conversion of heat into work.

Answer

There are no fundamental thermodynamic limitations on the efficiency of heat engines.

Question 32

Which of the following is **NOT** considered a thermodynamic system?

Accepted Answer

The entire universe

Answer

A closed container filled with gas

Answer

A piston moving within a cylinder

Answer

A mixture of two gases

Question 33

The First Law of Thermodynamics can be expressed mathematically as:

Accepted Answer

dU = δQ - δW

Answer

dQ = dU - δW

Answer

δW = dU - δQ

Answer

U = Q - W

Question 34

Which of the following processes is considered isobaric?

Accepted Answer

A piston moving within a cylinder while maintaining constant external pressure

Answer

A gas expanding into a vacuum

Answer

A gas being heated inside a sealed container

Answer

A gas being compressed within a cylinder

Question 35

What is the definition of molar specific heat capacity?

Accepted Answer

The amount of heat required to raise the temperature of one mole of a substance by one degree Celsius

Answer

The amount of heat required to raise the temperature of one kilogram of a substance by one degree Celsius

Answer

The amount of heat required to raise the temperature of one cubic meter of a substance by one degree Celsius

Answer

The amount of heat required to raise the temperature of one liter of a substance by one degree Celsius

Question 36

Which of the following is NOT an assumption of the ideal gas law?

Accepted Answer

The volume of gas particles is comparable to the container volume

Answer

Gas particles are point masses

Answer

Gas particles interact via negligible forces

Answer

Gas particles are in constant random motion

Question 37

The critical point of a substance is the point at which:

Accepted Answer

The liquid and gas phases possess identical properties

Answer

The liquid and solid phases possess identical properties

Answer

The gas and solid phases possess identical properties

Answer

The substance exhibits its lowest specific heat

Question 38

Which of the following statements regarding the Clausius-Clapeyron equation is **incorrect**?

Accepted Answer

It is solely applicable to ideal gases.

Answer

It relates changes in pressure and temperature to changes in vapor pressure.

Answer

It can be used to predict the enthalpy of vaporization of a substance.

Question 39

How do intermolecular forces impact the behavior of real gases compared to ideal gases?

Accepted Answer

Intermolecular forces in real gases cause gas molecules to attract each other.

Answer

Real gases have weaker intermolecular forces at higher temperatures than ideal gases.

Answer

Real gases exhibit weaker intermolecular forces at larger volumes compared to ideal gases.

Question 40

How does thermodynamics serve as a unifying foundation for fluid mechanics, heat transfer, and materials science?

Accepted Answer

Thermodynamics provides a common language to describe and analyze energy transfer and conversion processes across these fields.

Answer

Thermodynamics is only applicable to fluid mechanics and has no relevance to heat transfer or materials science.

Answer

Thermodynamics is unrelated to fluid mechanics, heat transfer, or materials science.

Question 41

In spontaneous processes, what happens to entropy?

Accepted Answer

Increases

Answer

Decreases

Answer

Stays the same

Question 42

How do thermodynamics principles guide the design and operation of a thermal power plant to enhance efficiency and minimize environmental impact?

Accepted Answer

Optimize heat transfer to reduce losses

Accepted Answer

Use regenerative cycles to preheat the working fluid

Accepted Answer

Minimize pressure drops within the system

Answer

Increase the temperature of the working fluid without considering other factors

Question 43

What is the significance of the Carnot cycle, and how does it relate to the maximum possible thermal efficiency of heat engines?

Accepted Answer

The Carnot cycle sets the theoretical limit for thermal efficiency, which no practical heat engine can surpass.

Answer

Heat engines can achieve efficiencies higher than the Carnot cycle efficiency.

Answer

The thermal efficiency of a heat engine depends only on the temperature of the heat source.

Question 44

An adiabatic process is one in which:

Accepted Answer

There is no heat transfer

Answer

There is no work transfer

Answer

The temperature remains constant

Answer

The pressure remains constant

Question 45

Which of the following is an example of a closed system?

Accepted Answer

A closed container filled with gas

Answer

A piston-cylinder with a leak

Answer

An open container filled with liquid

Answer

A room with an open window

Question 46

The thermal efficiency of a heat engine is defined as:

Accepted Answer

The ratio of the work output to the heat input

Answer

The ratio of the heat input to the work output

Answer

The difference between the heat input and the work output

Answer

The sum of the heat input and the work output

Question 47

Entropy of a system can be described as:

Accepted Answer

A measure of the system's disorder

Answer

A measure of the system's energy

Answer

A measure of the system's temperature

Answer

A measure of the system's pressure

Question 48

In a non-adiabatic process, which of the following is true regarding entropy generation and irreversibility?

Accepted Answer

Entropy generation is greater than zero, and irreversibility always occurs.

Answer

Entropy generation is zero, but irreversibility is possible.

Answer

Irreversibility can occur without entropy generation.

Answer

Entropy generation is less than zero, but irreversibility may still occur.

Question 49

On a phase diagram for water, where would you find the point representing 25°C and 1 atmosphere of pressure?

Accepted Answer

Liquid (water)

Answer

Solid (ice)

Answer

Gas (water vapor)

Answer

Supercritical fluid

Question 50

How do the first and second laws of thermodynamics inform our understanding of the spontaneity of a chemical reaction?

Accepted Answer

The first law determines the energy change, while the second law predicts the direction of entropy change, together indicating spontaneity.

Answer

The second law alone determines spontaneity based on the change in entropy.

Answer

The first law alone determines spontaneity based on the change in internal energy.

Answer

The second law alone determines spontaneity based on the change in Gibbs free energy.

Question 51

The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Question 52

Describe the significance of the critical point in phase diagrams and explain how it affects the behavior of substances during phase transitions.

Accepted Answer

At the critical point, the liquid and vapor phases become indistinguishable, exhibiting properties of both phases.

Answer

The critical point is only relevant to pure substances.

Answer

The critical point is always at a higher temperature and pressure than the normal boiling point.

Answer

The critical point has no practical significance in thermodynamics.

Question 53

Which of the following is **not** considered a thermodynamic property?

Accepted Answer

Velocity

Answer

Temperature

Answer

Pressure

Answer

Density

Question 54

A thermodynamic system can be defined as:

Accepted Answer

Any quantity of matter under examination

Answer

The surroundings influencing the system

Answer

The boundary separating the system from its surroundings

Answer

The energy exchanged between the system and its surroundings

Question 55

Which type of work is performed when a gas expands against an external pressure that remains constant?

Accepted Answer

Boundary work

Answer

Shaft work

Answer

Heat transfer

Answer

Electrical work

Question 56

Which of the following processes can be classified as isothermal?

Accepted Answer

A gas expanding in a vacuum

Answer

A gas being compressed in a piston

Answer

A gas cooling in a closed container

Answer

A gas heating up in a furnace

Question 57

What is the SI unit of entropy?

Accepted Answer

Joule per kelvin

Answer

Kelvin

Answer

Joule

Answer

Watt per kelvin

Question 58

The efficiency of a heat engine can be defined as:

Accepted Answer

The ratio of work output to heat input

Answer

The ratio of heat input to work output

Answer

The difference between work output and heat input

Answer

The product of work output and heat input

Question 59

Which of the following is a characteristic of a thermodynamic system?

Accepted Answer

Pressure

Answer

Acceleration

Answer

Displacement

Answer

Velocity

Question 60

The first law of thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed

Answer

Entropy always increases

Answer

Heat flows from hot to cold

Answer

The efficiency of a heat engine is always less than 100%

Question 61

The SI unit of energy is the:

Accepted Answer

Joule

Answer

Newton

Answer

Pascal

Answer

Kelvin

Question 62

In an isobaric process, the:

Accepted Answer

Pressure remains constant

Answer

Volume remains constant

Answer

Temperature remains constant

Answer

Entropy remains constant

Question 63

The thermal efficiency of a Carnot engine depends on:

Accepted Answer

The temperatures of the heat reservoirs

Answer

The type of working fluid

Answer

The size of the engine

Answer

The speed of the engine

Question 64

The Otto cycle is a type of:

Accepted Answer

Internal combustion engine cycle

Answer

Heat pump cycle

Answer

Refrigeration cycle

Answer

Power plant cycle