What is the name of the change of state that occurs when a substance changes from a solid to a liquid?
- boiling
- condensation
- evaporation
- melting
Show answer and explanation
Answer: D. melting
A solid changing to a liquid is melting.
O Level Physics: Thermal physics, questions with answers
Practise 53 real questions on Thermal physics from 2021 to 2026. See the answer and explanation as soon as you answer.
53real questions
37multiple choice
11exam sessions
About Thermal physics in O Level Physics
Thermal physics is one of the 14 main topics in our O Level Physics (Cambridge (CAIE) 5054) question bank, and about 8% of its real questions come from it. Tayyari Karo has 53 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2; 37 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 32 medium, 16 easy, 5 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
Boiling and evaporation are different processes. Which statement is correct?
- Boiling only occurs at the surface of a liquid.
- Evaporation only occurs when the temperature of the liquid is high enough.
- Evaporation does not change the temperature of a liquid.
- When a boiling liquid is heated its temperature remains constant.
Show answer and explanation
Answer: D. When a boiling liquid is heated its temperature remains constant.
During boiling, all the extra heat energy supplied goes into changing state, so the temperature stays constant at the boiling point.
An incomplete statement about latent heat is given.
Latent heat is the ......1...... required to overcome the bonds between molecules and change the ......2...... of a substance.
Which words correctly complete gap 1 and gap 2?
- gap 1 energy, gap 2 state
- gap 1 force, gap 2 state
- gap 1 energy, gap 2 temperature
- gap 1 force, gap 2 temperature
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Answer: A. gap 1 energy, gap 2 state
Latent heat is energy, and it is absorbed at constant temperature while the substance changes state.
In many applications, a thermocouple is used to measure temperature instead of a liquid-in-glass thermometer.
Which property of a thermocouple is a major advantage?
- its greater heat capacity
- its smaller temperature range
- its quicker response time
- its non-linear output
Show answer and explanation
Answer: C. its quicker response time
The thermocouple junction has a very small thermal capacity, so it reaches the temperature of its surroundings, and responds to changes, much faster than a liquid-in-glass thermometer.
Four thermometers P, Q, R and S have scales of the same physical length.
Thermometer P reads from 0 °C to 25 °C, thermometer Q reads from 30 °C to 40 °C, thermometer R reads from 0 °C to 250 °C and thermometer S reads from 100 °C to 300 °C.
Which thermometer has the greatest sensitivity and which thermometer has the greatest range?
- greatest sensitivity P, greatest range R
- greatest sensitivity P, greatest range S
- greatest sensitivity Q, greatest range R
- greatest sensitivity Q, greatest range S
Show answer and explanation
Answer: C. greatest sensitivity Q, greatest range R
Q spreads only 10 °C over the whole scale so it is the most sensitive, while R covers 250 °C compared with 200 °C for S so it has the greatest range.
What is the heat capacity of a body?
- the amount of thermal energy that the body can absorb without melting
- the amount of thermal energy required to raise the temperature of the body by 1.0 °C
- the amount of thermal energy required to raise the temperature of 1.0 kg of the body by 1.0 °C
- the amount of thermal energy required to raise the temperature of 1.0 m³ of the body by 1.0 °C
Show answer and explanation
Answer: B. the amount of thermal energy required to raise the temperature of the body by 1.0 °C
Heat capacity refers to the whole body, not to one kilogram or one cubic metre of it, and is the energy needed to raise its temperature by 1 °C.
A pan containing ice at −15 °C is placed on a gas heater. Thermal conduction occurs in the metal from which the pan is made. By referring to particles, describe the process of thermal conduction in a metal.
Show model answer
Particles at the hot part of the metal vibrate more vigorously and pass on this vibrational energy to neighbouring particles through collisions; metals also contain free (delocalised) electrons which move through the metal, carrying kinetic energy quickly from the hot region to the cold region, making metals good thermal conductors.
Conduction in metals occurs both through particle vibration passed between neighbours and through fast-moving free electrons.
Explain why the temperature of the water is constant as the ice melts.
Show model answer
While melting, all the energy supplied is used to break/weaken the bonds between the particles (increasing their potential energy) as the solid changes to liquid, rather than increasing the particles' kinetic energy, so the temperature does not rise until melting is complete.
Energy supplied during a change of state goes into potential energy (breaking bonds), not kinetic energy (temperature).
Sessions with Thermal physics questions
| Session | Paper 1 | Paper 2 |
|---|---|---|
| May/June 2026 | 4 | – |
| May/June 2025 | – | 1 |
| Oct/Nov 2025 | 1 | 2 |
| May/June 2024 | 4 | 6 |
| Oct/Nov 2024 | 3 | 1 |
| May/June 2023 | 3 | 1 |
| Oct/Nov 2023 | 3 | 1 |
| May/June 2022 | 4 | 1 |
| Oct/Nov 2022 | 6 | – |
| May/June 2021 | 4 | 1 |
| Oct/Nov 2021 | 5 | 2 |
Common questions
What does the Thermal physics topic cover on this page?
53 real O Level Physics (5054) questions on Thermal physics from 2021 to 2026, from Paper 1, Paper 2. Each one shows the year, session and paper it came from.
Do I get the answers and explanations?
Yes. Every question shows the correct answer and a short explanation the moment you answer.
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You can start free with no signup. A small set of papers per subject is free, and Premium unlocks every paper, the full question bank and the paper PDFs.