Phase Transitions in Physics: Interactive Quizzes for BSc Students

Question 1

Which of the following accurately describes melting?

Accepted Answer

A phase transition where a solid transforms into a liquid

Answer

A process occurring when the temperature of a substance decreases

Answer

A change accompanied by a release of energy

Answer

An irreversible transformation

Question 2

During vaporization, as a liquid transforms into a gas, what occurs to the intermolecular forces?

Accepted Answer

They weaken

Answer

They strengthen

Answer

They remain unchanged

Answer

They reverse direction

Question 3

Which factor does NOT influence the rate of melting?

Accepted Answer

Volume of the substance

Answer

Surface area of the substance

Answer

Temperature of the surroundings

Answer

Applied pressure

Question 4

What is the significance of a substance's enthalpy of fusion?

Accepted Answer

It indicates the heat required to melt one mole of the substance

Answer

It determines the substance's melting point

Answer

It provides information about entropy change during melting

Answer

It measures the solidity of the solid phase

Question 5

A substance's triple point is characterized by a temperature of -42°C and a pressure of 0.15 atm. What does this imply?

Accepted Answer

At this specific temperature and pressure, the substance can coexist in solid, liquid, and gas phases

Answer

Above this temperature and pressure, the substance will solely exist as a gas

Answer

Below this temperature and pressure, the substance will only be present as a solid

Answer

Phase transitions will not occur at this temperature and pressure

Question 6

How is a first-order phase transition distinct from a second-order phase transition?

Accepted Answer

First-order transitions exhibit entropy discontinuity, unlike second-order transitions

Answer

Second-order transitions are always reversible, while first-order transitions are not

Answer

First-order transitions occur at a specific temperature and pressure, whereas second-order transitions occur over a range

Answer

Second-order transitions involve a change in crystal structure, but first-order transitions do not

Question 7

Define the critical point of a substance

Accepted Answer

The point where liquid and gas phases become indistinguishable

Answer

The point where solid, liquid, and gas phases coexist

Answer

The point of highest density

Answer

The point of highest vapor pressure

Question 8

Which statement is true about the Clausius-Clapeyron equation?

Accepted Answer

It calculates the vapor pressure of a substance at a specific temperature.

Answer

It relates pressure, volume, and temperature of a gas.

Answer

It applies only to ideal gases.

Answer

It determines the Gibbs free energy of a phase transition.

Question 9

What is the physical significance of the triple point?

Accepted Answer

Equilibrium coexistence of solid, liquid, and gas phases

Answer

Equal vapor pressure and atmospheric pressure

Answer

Equal melting point and boiling point

Answer

Equal density in solid, liquid, and gas phases

Question 10

Explain the critical point.

Accepted Answer

Vanishing distinction between liquid and gas phases

Answer

Zero vapor pressure

Answer

Equal melting and freezing points

Answer

Equal density in liquid and gas phases

Question 11

Provide an example of a phase transition in biological systems.

Accepted Answer

Folding of proteins

Answer

Melting of ice

Answer

Evaporation of water

Answer

Condensation of steam

Question 12

What is the latent heat of fusion of a substance?

Accepted Answer

The amount of heat required to change 1 kg of a substance from a solid to a liquid at its melting point at constant pressure.

Answer

The amount of heat released when 1 kg of a substance condenses from a gas to a liquid at its boiling point at constant pressure.

Answer

The specific heat capacity of a substance in its liquid phase.

Answer

The change in entropy of a substance when it undergoes a phase transition.

Question 13

What is the Clausius-Clapeyron equation primarily used for?

Accepted Answer

Calculating the vapor pressure of a liquid as a function of temperature.

Answer

Calculating the enthalpy of vaporization of a liquid.

Answer

Calculating the boiling point of a liquid as a function of pressure.

Answer

Calculating the critical temperature of a gas.

Question 14

What is the significance of the triple point of a substance?

Accepted Answer

It is the only point at which the solid, liquid, and gas phases can coexist in equilibrium.

Answer

It is the point at which the melting point, boiling point, and critical point of a substance coincide.

Answer

It is the point at which the vapor pressure of a solid is equal to the vapor pressure of its liquid.

Answer

It is the point at which the specific heat capacity of a substance reaches its maximum.

Question 15

Which of the following statements about phase diagrams is accurate?

Accepted Answer

Phase diagrams can be used to predict the phase behaviour of a substance under different conditions of temperature and pressure.

Answer

Phase diagrams are only useful for pure substances.

Answer

Phase diagrams are always symmetrical about the melting line.

Answer

Phase diagrams are independent of the amount of substance present.

Question 16

When a liquid transforms into a gas, this process is known as:

Accepted Answer

Vaporization

Answer

Melting

Answer

Freezing

Answer

Sublimation

Question 17

Which factor does not influence the melting point of a substance?

Accepted Answer

Temperature

Answer

Pressure

Answer

Impurities

Answer

Chemical composition

Question 18

What term describes the energy needed to change a substance from one phase to another?

Accepted Answer

Latent heat

Answer

Specific heat

Answer

Internal energy

Answer

Enthalpy

Question 19

What is the name of the graphical representation showing the relationship between temperature, pressure, and volume for a substance?

Accepted Answer

Phase diagram

Answer

Gibbs phase rule

Answer

Clapeyron equation

Answer

Maxwell's equations

Question 20

What is the critical point of a substance?

Accepted Answer

The point where liquid and gas phases become indistinguishable

Answer

The point where solid and liquid phases become indistinguishable

Answer

The point where gas and plasma phases become indistinguishable

Answer

The point where all three phases coexist

Question 21

What is the term for a phase transition without a change in temperature?

Accepted Answer

Isothermal

Answer

Isentropic

Answer

Adiabatic

Answer

Isobaric

Question 22

When a liquid turns into a gas, it absorbs energy. This energy is primarily used to:

Accepted Answer

Break apart intermolecular bonds

Answer

Form new intermolecular bonds

Answer

Increase the kinetic energy of molecules

Answer

Decrease the kinetic energy of molecules

Question 23

The temperature at which a solid melts is known as its:

Accepted Answer

Melting point

Answer

Freezing point

Answer

Boiling point

Answer

Evaporation point

Question 24

During sublimation, a substance changes directly from:

Accepted Answer

Solid to gas

Answer

Solid to liquid

Answer

Liquid to gas

Answer

Gas to solid

Question 25

The entropy of a system generally:

Accepted Answer

Increases during a phase transition

Answer

Decreases during a phase transition

Answer

Remains constant during a phase transition

Answer

Can either increase or decrease depending on the transition