Solids, Liquids and Gases Exam Questions
Practice IGCSE Chemistry exam questions on solids, liquids and gases. Covers particle arrangement, properties of each state, and explaining macroscopic behaviour using kinetic particle theory with mark schemes and examiner notes.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
These questions cover the properties and particle models of solids, liquids and gases. Write each answer fully before checking the mark scheme.
Question 1 (3 marks, Core)
Describe the arrangement and movement of particles in a solid, a liquid, and a gas.
Mark scheme
- Solid: particles are closely packed in a regular/fixed arrangement and vibrate about fixed positions [1]
- Liquid: particles are close together but in an irregular arrangement and can slide past each other [1]
- Gas: particles are far apart with no fixed arrangement and move rapidly in random directions [1]
Examiner note: Each mark requires both arrangement and movement. Writing “particles are close together” for a liquid without mentioning sliding/movement scores 0 for that state.
Question 2 (3 marks, Core)
A student pours water from a beaker into a differently shaped container.
(a) Explain why the water takes the shape of the new container but keeps the same volume. (2)
(b) Explain why a solid block would not do the same. (1)
Mark scheme
(a) In a liquid, particles can slide past each other so the liquid flows to take the shape of the container [1]. The particles are still close together with forces between them, so the volume stays the same [1].
(b) In a solid, particles are held in fixed positions and cannot move past each other, so it keeps its shape [1]
Examiner note: “Liquids have no fixed shape” is a statement, not an explanation. You must refer to particle movement to explain why they have no fixed shape.
Question 3 (4 marks, Core)
The table below shows some properties of three substances at room temperature.
| Substance | Shape | Volume | Compressibility | Density |
|---|---|---|---|---|
| A | Fixed | Fixed | Very low | High |
| B | Takes container shape | Fixed | Very low | Medium |
| C | Fills container | Fills container | High | Very low |
(a) Identify the state of matter of substance A, B, and C. (1)
(b) Explain, in terms of particles, why substance C is easily compressed but substance B is not. (3)
Mark scheme
(a) A = solid, B = liquid, C = gas [1] (all three correct for the mark)
(b) In C (gas), particles are far apart with large spaces between them [1], so particles can be pushed closer together when force is applied [1]. In B (liquid), particles are already close together with very little space between them, so they cannot be pushed much closer [1].
Examiner note: This is a comparison question — writing about only the gas limits you to 2 marks. You must contrast gas and liquid particle spacing.
Question 4 (2 marks, Core)
A sealed syringe contains air. When the plunger is pushed in, the volume decreases.
Explain why this is possible for a gas but not for a liquid trapped in a sealed syringe.
Mark scheme
- Gas particles are far apart / have large spaces between them, so can be pushed closer together [1]
- Liquid particles are already close together / touching, so cannot be compressed significantly [1]
Examiner note: Do not say gas particles are “smaller” — the particles themselves are the same size. It is the spacing between particles that differs.
Question 5 (4 marks, Supplement)
Use kinetic particle theory to explain the following observations:
(a) Gases exert pressure on the walls of their container. (2)
(b) Increasing the temperature of a gas in a sealed container increases the pressure. (2)
Mark scheme
(a) Gas particles move randomly at high speed [1] and collide with the walls of the container, exerting a force on them / the many collisions per second produce a net force on the walls [1]
(b) Higher temperature gives particles more kinetic energy so they move faster [1]. They hit the walls more frequently and with greater force, so the pressure increases [1].
Examiner note: “More collisions” alone is worth 1 mark. Full marks require both increased frequency and increased force of collisions, or explicitly linking temperature to kinetic energy.
Question 6 (3 marks, Supplement)
The diagrams below represent the arrangement of particles in three substances, P, Q, and R.
P: particles in an ordered, closely packed arrangement Q: particles close but disordered R: particles widely spaced and randomly distributed
(a) Identify the state of matter of P, Q, and R. (1)
(b) State which substance has the highest kinetic energy per particle at the same temperature. (1)
(c) Explain your answer to (b). (1)
Mark scheme
(a) P = solid, Q = liquid, R = gas [1]
(b) All three have the same (average) kinetic energy [1]
(c) At the same temperature, particles in all states have the same average kinetic energy [1]
Examiner note: This is a common misconception question. Temperature determines average kinetic energy, not the state. Many candidates incorrectly choose the gas. Gas particles move faster but have the same average KE as solid and liquid particles at the same temperature.
Question 7 (2 marks, Core)
A drop of ink is placed in cold water and in hot water at the same time.
State and explain which beaker will become uniformly coloured first.
Mark scheme
- The hot water will become uniformly coloured first [1]
- At a higher temperature the particles have more kinetic energy and move faster, so diffusion is faster [1]
Examiner note: Simply saying “hot water spreads faster” without a particle explanation scores only 1 mark. Link temperature to kinetic energy to speed of particles.
Question 8 (3 marks, Core)
Explain, using ideas about particles, why:
(a) solids have a fixed shape but liquids do not. (2)
(b) liquids and gases can flow but solids cannot. (1)
Mark scheme
(a) In solids, particles are held in fixed positions by strong forces and can only vibrate [1]. In liquids, particles can slide past each other so the substance takes the shape of the container [1].
(b) In liquids and gases, the particles are free to move past each other / are not held in fixed positions [1]
Examiner note: Avoid vague language like “solids are hard.” The question demands a particle-level explanation. “Particles vibrate in fixed positions” is the key phrase for solids.
What to revise if you scored below 6
If you dropped marks on the comparison questions (3, 4), make sure you can draw and label particle diagrams for all three states. Revisit the solids, liquids and gases notes and practise writing particle explanations for everyday observations — the examiners always want the microscopic reason behind the macroscopic property.
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