Practise 31 exam-style questions on The three states of matter for AQA GCSE Chemistry. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
31 questions
1–6 marks each
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20 questions, marked as you go
Sample questions with model answers
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Question 1
1 mark
In the simple particle model, particles are represented by small solid spheres.
Give one limitation of this model.
Model answer
The model does not show any forces between the particles.
Explanation
The model shows arrangement and movement well, but in reality there are forces of attraction between particles, real particles (such as molecules) are not all spheres, and atoms are not solid balls. These limitations matter when explaining changes of state.
Mark scheme
1 mark
there are no forces between the particles in the model
max 1
1 mark
all particles are represented as spheres (real particles have different shapes)
1 mark
the spheres are solid (real atoms are mostly empty space / contain smaller particles)
allow spheres are inelastic / cannot change shape
Question 2
2 marks
Some crushed ice was heated at a constant rate. The ice took 4 minutes to melt at 0 °C, but the water then took 27 minutes to boil away at 100 °C.
Suggest why boiling took much longer than melting.
Model answer
More energy is needed to boil the water than to melt the ice. When ice melts only some of the forces between the particles are overcome and the particles stay close together, but when water boils the forces must be overcome completely so that the particles can separate and move far apart.
Explanation
Heating at a constant rate means the time taken is a measure of the energy needed. Separating particles completely into a gas needs far more energy than loosening them enough to slide past each other in a liquid.
Mark scheme
1 mark
more energy is needed to boil the water than to melt the ice
1 mark
in boiling, the forces of attraction between particles must be overcome completely so the particles separate, but in melting only some of the forces are overcome
allow 'particles must move far apart when boiling, but stay close together when melting'
Question 3
3 marks
On a cold day, water vapour in the air condenses on the inside of a window.
Explain, in terms of particles and energy, what happens when the water vapour condenses.
Model answer
The water particles hit the cold glass and transfer energy to it, so they lose energy and move more slowly. The particles come closer together and the forces of attraction between them hold them together, so they form liquid water on the window.
Explanation
Condensing is the reverse of boiling. Particles must lose energy so that the forces of attraction between them can hold them close together. Energy is transferred from the gas to the colder surroundings, here the window.
Mark scheme
1 mark
the particles transfer energy to the cold window / lose energy
allow particles cool down
1 mark
the particles move more slowly and come closer together
either idea
1 mark
forces of attraction (form between the particles and) hold the particles together as a liquid
allow intermolecular forces; do not accept 'covalent bonds form'
Question 4
4 marks
A teacher uses small plastic balls in a tray to model a solid melting. The balls start in neat rows touching each other. When the tray is shaken harder, the balls leave their rows and roll around each other.
Evaluate how well this model represents what happens to the particles when a solid melts.
Model answer
The model is useful because it shows particles changing from a regular arrangement, touching each other, to a random arrangement where they are still close together but can move around each other. Shaking harder represents the particles gaining energy. However, there are no forces of attraction between the balls, so the model cannot show that energy is needed to overcome these forces, or explain why the solid melts at a particular temperature. Also, real particles are not all spheres and are not solid. Overall the model shows the arrangement well but cannot explain the energy changes.
Explanation
An evaluation needs both strengths and weaknesses, and ideally a judgement. The big weakness of any solid-sphere model is that it has no forces between particles, and forces are what melting is all about.
Mark scheme
1 mark
strength: it shows the change from a regular arrangement to a random arrangement / particles still close together after melting
max 4; max 3 if no strength is given
1 mark
strength: shaking harder represents the particles gaining energy and vibrating more
1 mark
limitation: there are no forces of attraction between the balls
1 mark
so it cannot show that energy is needed to overcome the forces between particles / cannot explain the melting point
1 mark
limitation: real particles are not all spheres / not all the same shape
1 mark
limitation: real particles are not solid (atoms are mostly empty space)
allow balls are inelastic
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