10 free IGCSE Chemistry States of Matter questions written in the style of Cambridge Chemistry papers: 4 multiple-choice and 6 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Solids, liquids & gases, Diffusion. Work through the questions below, then generate a full States of Matter paper with a fresh set every time.
Generate a full States of Matter paper →A substance is heated steadily from solid to gas. Its temperature is measured every minute.
1 The temperature stays constant while the substance melts.
2 A pure substance melts over a range of temperatures.
3 The particles move faster while the substance is boiling.
Which statements are correct?
Answer: D
Which gas would diffuse most slowly at room temperature?
Answer: C
Which change of state needs energy to be taken in?
Answer: A
What effect does increasing temperature have on the rate of diffusion?
Answer: B
A sample of a substance is cooled from 120 °C to 20 °C. Its melting point is 80 °C and its boiling point is 110 °C.
State the physical state of the substance at 120 °C, at 95 °C and at 20 °C.
Explain why the temperature stays constant while the substance freezes.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | gas, liquid, solid 120 °C gas B1 95 °C liquid B1 20 °C solid B1 | 3 |
| (b) | energy released as forces form energy is released as attractive forces form between particles B1 this balances the energy lost to the surroundings B1 | 2 |
A porous pot filled with air is placed upside down over a beaker of hydrogen. A U-tube manometer is attached to the pot.
Predict what happens to the pressure inside the pot at first.
Explain your answer.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | increases it increases B1 | 1 |
| (b) | hydrogen diffuses in faster than air out hydrogen molecules are lighter B1 they diffuse into the pot faster than air molecules diffuse out B1 | 2 |
A student heats a sample of salol until it melts, then lets it cool, recording its temperature every minute. Fig. 7.1 shows the cooling curve.
Use Fig. 7.1 to find the melting point of the substance.
State what is happening to the substance between 2 and 6 minutes.
Explain why the temperature stays constant between 2 and 6 minutes.
Describe the changes in the arrangement and motion of the particles as the liquid freezes.
Explain why a gas can be compressed easily but a liquid cannot.
Suggest why the student uses a water bath rather than a Bunsen burner to heat the substance.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 43 °C 43 °C B1 | 1 |
| (b) | freezing / solidifying it is freezing (changing from liquid to solid) B1 | 1 |
| (c) | energy released as bonds/forces form between particles; balances energy lost to surroundings attractive forces form between the particles as the solid forms B1 energy is released B1 this balances the energy lost to the surroundings, so the temperature does not fall B1 | 3 |
| (d) | liquid: random, moving past each other; solid: regular lattice, vibrate in fixed positions; particles slow down in the liquid the particles are randomly arranged and slide past each other B1 in the solid they are in a regular arrangement B1 they only vibrate about fixed positions (less kinetic energy) B1 | 3 |
| (e) | gas particles far apart; liquid particles touching gas particles are far apart with large spaces between them B1 liquid particles are close together / touching B1 | 2 |
| (f) | even, controlled heating; substance is flammable / below 100 °C gives gentle, even heating B1 the substance is flammable / melts below 100 °C B1 | 2 |
Ice cubes melt in a glass of water on a warm day.
Describe what happens to the particles of ice as it melts.
State the term for a solid changing directly into a gas.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | vibrate more, break from fixed positions particles gain energy and vibrate more B1 they break free from their fixed positions and can move past each other B1 | 2 |
| (b) | sublimation sublimation B1 | 1 |
Gases diffuse at different rates.
State the relationship between the relative molecular mass of a gas and its rate of diffusion.
Place these gases in order of rate of diffusion, fastest first: carbon dioxide, hydrogen, nitrogen.
Explain why diffusion in liquids is slower than in gases.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | lower Mr diffuses faster the lower the Mr, the faster the gas diffuses B1 | 1 |
| (b) | H₂, N₂, CO₂ hydrogen, nitrogen, carbon dioxide B1 | 1 |
| (c) | particles closer, more collisions, move slower liquid particles are close together B1 they collide frequently and move more slowly, so they mix more slowly B1 | 2 |
A purple crystal of potassium manganate(VII) is placed at the bottom of a beaker of water. After a few hours the purple colour has spread through all of the water.
Explain these observations using the kinetic particle theory.
Suggest why diffusion is faster in a gas than in a liquid.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | random movement, high to low concentration the particles of the crystal dissolve and move randomly B1 they move from a region of high concentration to low concentration B1 until they are evenly spread B1 | 3 |
| (b) | gas particles move faster / more space gas particles move faster and have more space between them B1 | 1 |
In the 0620 syllabus, States of Matter covers Solids, liquids & gases, Diffusion.
This page has 10 States of Matter questions with answers. For more, the free generator on mentorriyaz.in builds a new States of Matter paper with a full mark scheme each time you click.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in