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Pre AP Chemistry -1.2C Particle Attractions and Phase Changes- MCQ Exam Style Questions -New Syllabus 2025-2026

Pre AP Chemistry -1.2C Particle Attractions and Phase Changes- MCQ Exam Style Questions – New Syllabus 2025-2026

Pre AP Chemistry -1.2C Particle Attractions and Phase Changes- MCQ Exam Style Questions – Pre AP Chemistry – per latest Pre AP Chemistry Syllabus.

Pre AP Chemistry – MCQ Exam Style Questions- All Topics

Question 

A compound, X, has a melting point of 71°C and a boiling point of 375°C.

Which statement about X is correct?

A) It is a liquid at 52°C and a gas at 175°C.
B) It is a liquid at 69°C and a gas at 380°C.
C) It is a liquid at 75°C and a gas at 350°C.
D) It is a liquid at 80°C and a gas at 400°C.

▶️ Answer/Explanation
Solution

Ans: D

To determine the state of a substance at different temperatures, we compare the given temperature to its melting and boiling points:

  • Below melting point: solid
  • Between melting and boiling points: liquid
  • Above boiling point: gas

Analyzing each option:

A) 52°C is below melting point (should be solid), 175°C is below boiling point (should be liquid). Incorrect.

B) 69°C is below melting point (should be solid), 380°C is just above boiling point (correct for gas). Partially correct but not fully.

C) 75°C is above melting point (correct for liquid), but 350°C is below boiling point (should be liquid, not gas). Incorrect.

D) 80°C is above melting point (correct for liquid), 400°C is above boiling point (correct for gas). Fully correct.

Question 

Four processes are listed.

  1. Brownian motion
  2. condensation
  3. diffusion
  4. evaporation

Which processes involve a change of state?

A 1 and 2    B 1 and 3    C 2 and 4    D 3 and 4

▶️ Answer/Explanation
Solution

Ans: C

Processes involving a change of state are those where matter transitions between solid, liquid, and gas phases. Here:

  • Condensation (2): Gas → Liquid
  • Evaporation (4): Liquid → Gas

Brownian motion (1) and diffusion (3) describe particle movement within a state (e.g., gas or liquid) and do not involve phase changes. Thus, the correct pair is 2 and 4 (Option C).

Question 

The diagram shows how the arrangement of particles changes when a substance changes state.
Which change of state is shown?


A) boiling
B) condensation
C) evaporation
D) sublimation

▶️ Answer/Explanation
Solution

Ans: D

The diagram shows a direct transition from a solid (where particles are tightly packed in a fixed arrangement) to a gas (where particles are widely spaced and move freely). This bypasses the liquid phase entirely.

Sublimation is the process where a solid turns directly into a gas without becoming a liquid first. Examples include dry ice (solid CO₂) or iodine crystals. Since the change matches this description, the correct answer is D (sublimation).

Question 

The diagram shows some changes of state.

Which words describe the changes of state, P, Q, R and S?

▶️ Answer/Explanation
Solution

Ans: B

P (Melting): Solid → Liquid. Heat is absorbed, breaking intermolecular forces.

Q (Evaporation): Liquid → Gas. High-energy particles escape the liquid phase.

R (Freezing): Liquid → Solid. Heat is released, forming an ordered structure.

S (Condensation): Gas → Liquid. Particles lose energy and coalesce.

Thus, the correct sequence is B (P-Melting, Q-Evaporation, R-Freezing, S-Condensation).

Question 

The changes that occur when a substance changes state are shown below.

Which process, W, X, Y or Z, is occurring in the following four situations?

  1. Butter melts on a warm day.
  2. Water condenses on a cold surface.
  3. The volume of liquid ethanol in an open beaker reduces.
  4. Ice forms inside a freezer.

▶️ Answer/Explanation
Solution

Ans: B

1. Butter melting (W): Solid to liquid transition (melting).
2. Water condensing (Y): Gas to liquid transition (condensation).
3. Ethanol evaporating (X): Liquid to gas transition (evaporation).
4. Ice forming (Z): Liquid to solid transition (freezing).
The correct sequence is W, Y, X, Z, matching option B.

Question 

What are the processes W, X, Y and Z in the following diagram?


▶️ Answer/Explanation
Solution

Ans: C

The diagram shows phase changes between solid, liquid, and gas states:

  1. W (Solid → Liquid): Melting – Particles gain energy to overcome fixed positions.
  2. X (Liquid → Gas): Boiling/Evaporation – High-energy particles escape as gas.
  3. Y (Liquid → Solid): Freezing – Particles lose energy and form ordered structure.
  4. Z (Gas → Liquid): Condensation – Gas particles cool and coalesce into liquid.

Thus, the correct sequence is W: melting, X: boiling, Y: freezing, Z: condensing, matching option C.

Questions

Which row explains how increasing the surface area of a fixed volume of liquid water and blowing air over the surface speeds up evaporation?

▶️Answer/Explanation

Ans D

Question

A quantity of water is boiled to form the same mass of steam.
Which row shows how the volume and density of the water change?

▶️Answer/Explanation

Ans: C

Question

Which row describes the process of melting?

▶️Answer/Explanation

Ans: D

Question

Which name is given to the change of state when steam at 100° C changes to water at 100° C?

A) boiling
B) condensation
C) evaporation
D) melting

▶️Answer/Explanation

Ans: B

Question

A textbook gives the description of a thermal process as ‘more-energetic molecules escape from the surface of a liquid which causes the liquid to cool’. Which process is being described?
A boiling
B Brownian motion
C condensation
D evaporation

▶️Answer/Explanation

Ans D

Question

Some terms describing changes of state are listed.

1 boiling
2 solidification
3 condensation
4 evaporation

Which two terms identify the same change of state?

A 1 and 3

B 1 and 4

C 2 and 3

D 2 and 4

▶️Answer/Explanation

Ans B

Question

 The diagram shows four labelled changes of state between solid, liquid and gas.


Which changes need an energy input?
A $P$ and $Q$
B $Q$ and $R$
C R and $\mathrm{S}$
D $S$ and $P$

Answer/Explanation

Ans:A

Question

The melting point of a substance is –78 °C and its boiling point is 23 °C.
Which row gives the correct state of matter of the substance at the given temperatures?

Answer/Explanation

Ans:D

Question

 The table lists the melting points and the boiling points of four different substances.
Which substance is a liquid at $0^{\circ} \mathrm{C}$ ?

Answer/Explanation

Ans:B

Question

Rods of the same shape and size are inserted through corks into a tank of hot water. Each rod is

covered with a layer of solid wax that has a low melting point. After a period of time, some wax melts.

                           

On which rod will the wax melt first?

  1. all at the same time

  2. good thermal conductor

  3. bad thermal conductor

  4. moderate thermal conductor

Answer/Explanation

Ans: B

Question

It is a warm and humid day. A glass contains an iced drink. Water starts to form on the outside of the glass.

image

What is the name of the effect by which the water forms?

  1. condensation

  2. conduction

  3.  convection

  4.  evaporation

Answer/Explanation

Ans: A

Question

A substance loses thermal energy (heat) to the surroundings at a steady rate.

The graph shows how the temperature of the substance changes with time.

                 

What could the portion PQ of the graph represent?

  1. gas condensing

  2. gas cooling

  3. liquid cooling

  4. liquid solidifying

Answer/Explanation

Ans: C

Question

The liquid level in a thermometer rises when the thermometer is placed in hot water. What causes this?
A The liquid contracts.
B The liquid evaporates.
C The liquid expands.
D The liquid freezes.

▶️Answer/Explanation

Ans C

Question

An ice cube is placed in a beaker and is heated. The ice melts to form water, which evaporates at first and then boils. The steam condenses on a cold window in the room. Which process involves a transfer of energy from the ice, water or steam to the surroundings?
A melting
B evaporating
C boiling
D condensing

▶️Answer/Explanation

Ans D

Question

A man puts some ice into a glass of water on a warm day. After a short time, he notices that the ice disappears and that water droplets appear on the outside of the glass.

Which two changes of state are taking place?
A condensation and freezing
B condensation and melting
C boiling and melting
D freezing and evaporation

▶️Answer/Explanation

Ans B

Question

An ice cube is placed in a beaker and is heated. The ice melts to form water, which evaporates at first and then boils. The steam condenses on a cold window in the room. Which process involves a transfer of energy from the ice, water or steam to the surroundings?
A melting
B evaporating
C boiling
D condensing

▶️Answer/Explanation

Ans D

Question

An ice cube is placed in a beaker and is heated. The ice melts to form water, which evaporates at first and then boils. The steam condenses on a cold window in the room. Which process involves a transfer of energy from the ice, water or steam to the surroundings?
A melting
B evaporating
C boiling
D condensing

▶️Answer/Explanation

Ans D

Question

Equal masses of two different liquids are put into identical beakers.

Liquid 1 is heated for 100 s and liquid 2 is heated for 200 s by heaters of the same power.

Each liquid has the same rise in temperature.

               

Which statement is correct?

A. Each beaker of liquid has the same thermal capacity.

B. Each beaker of liquid receives the same energy.

C. Liquid 1 receives more energy than liquid 2.

D. The thermal capacity of liquid 1 is less than the thermal capacity of liquid 2.

Answer/Explanation

Ans: D

Question

A solid is heated from room temperature.

The graph shows how its temperature changes with time as it is heated constantly.

At which time has it just become completely liquid?

     

Answer/Explanation

Ans: C

Questions

What are the correct terms for each change of state?

▶️Answer/Explanation

Ans C

Questions 

Which statement correctly describes a change of state?
A A gas condenses to form a liquid.
B A liquid melts to form a solid.
C A solid condenses to form a liquid.
D A solid boils to form a gas.

▶️Answer/Explanation

Ans A

Question

Gases can be compressed, but liquids cannot.

Which statement explains this difference?

A. Each molecule in a gas is more compressible than each molecule in a liquid.

B. Molecules in a gas are further apart than molecules in a liquid.

C. Molecules in a gas attract each other more strongly than molecules in a liquid.

D. Molecules in a gas move more slowly than molecules in a liquid.

Answer/Explanation

Ans: B

Question

At –39 °C, liquid mercury solidifies without a change of temperature.

Which row shows whether the mercury absorbs or releases energy and what happens to the

bonds between the mercury atoms?

 

energy

bonds between atoms

A

absorbed

stronger

B

absorbed

weaker

C

released

stronger

D

released

weaker

Answer/Explanation

Ans: C

Question

Two states of matter are described as follows.

In state 1, the molecules are very far apart. They move about very quickly at random in straight

lines until they hit something.

In state 2, the molecules are quite closely packed together. They move about at random. They do

not have fixed positions.

What is state 1 and what is state 2?

 

state 1

state 2

A

gas

liquid

B

gas

solid

C

liquid

gas

D

solid

liquid

Answer/Explanation

Ans: A

Question

Some ice is slowly heated and its temperature is measured. A graph is plotted of temperature against time.

Which row describes what happens to the thermal energy and to the temperature in section X?

Answer/Explanation

Ans:

B

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