Key Stage 3 Science Book 2 Assessments
Explaining Physical Changes (Purple level)
1. An ice cube is placed on the bench in a lab at normal room temperature. An hour later, nothing is to
be seen of it. Assuming nobody has moved it, which of these describes the sequence of processes? (1
mark)
a) melting, boiling
b) melting, evaporation
c) sublimation
d) melting, evaporation, boiling
2. A metal bar, when heated strongly, expands. Which of these statements is untrue? (1 mark)
a) It gets thicker and taller as well as longer.
b) It expands because the particles are moving around more.
c) It expands because the individual particles are expanding
d) If allowed to cool it will return to its original size
3. What is the name given to the energy that is transferred to a solid when it melts? [1 mark]
a) Latent heat
b) Boiling point
c) Melting point
d) Change of state
4. Ethanol, a colourless liquid, is soluble in water. Which of these is the best explanation of this
property? [1 mark]
a) The intermolecular bonds between water particles and ethanol particles
are stronger than intermolecular bonds between ethanol particles
b) It is transparent because light passes through it and is not absorbed
c) It has a low boiling point because the intermolecular bonds between
ethanol particles are weak
d) It is a neutral liquid (pH 7)
5. Why is the mass of one litre of chlorine greater than the mass of one litre of helium? [1 mark]
a) Particles of chlorine are closer together than particles of helium
b) Particles of chlorine have a greater mass than particles of helium
c) Particles of chlorine are bigger than particles of helium
d) Particles of chlorine move faster than particles of helium
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 2 Assessments
6. A 200 g rock contains 1.2 g of silver, but only 0.9 g are extracted. What is the efficiency of extraction?
[1 mark]
a) 35 %
b) 55 %
c) 75 %
d) 95 %
7. Which of these is not a chemical change? [1 mark]
a) Sodium left in air
b) Decomposition of copper carbonate
c) Heating iodine
d) Magnesium reacting with chlorine
8. What happens to the pressure in a car’s tyre when the car is driven and road friction increases the
temperature of the tyre? [1 mark]
a) It decreases
b) It remains the same
c) It increases
9. Complete the following sentence. [1 mark]
Sublimation is...
a) ...the burying of an object underground
b) ...the industrial process of making lime
c) ...a reaction that takes place under water
d) ...when a solid changes straight to a gas without going through the liquid phase
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 2 Assessments
10. Match the sentences to the correct endings. [1 mark]
Dissolving sugar in water does not change __
greater than the density of water
The density of sugar solution is __
the volume significantly
The more sugar dissolved in water the __
less than the density of sugar
solution
If water is poured carefully on to sugar
solution __
decrease with increasing
temperature
The density of water is __
greater the density of the solution
The densities of water and sugar solutions __
it floats on the surface initially, but
then mixes by diffusion
11. Which two statements about water boiling and evaporating are true? [1 mark]
a) These changes only happen at 100 degrees Celsius
b) These changes can happen at any temperature between 0 degrees
Celsius and 100 degrees Celsius
c) Water particles escape and produce a gas
d) Water particles have sufficient energy to escape from the liquid
12. Look at the diagram. It shows a particle model to demonstrate the changes when calcium carbonate
is added to hydrochloric acid.
Which two statements about the reaction between calcium carbonate and hydrochloric acid are true? [1
mark]
a) Oxygen atoms used to make calcium carbonate particles rearrange and combine with
other atoms to make particles of carbon dioxide and water
b) Oxygen atoms are rearranged and equal numbers are used to make particles of carbon
dioxide and water
c) Two particles of hydrochloric acid are needed because each particle is made from just
one hydrogen atom and one chlorine atom
d) Oxygen atoms and chlorine atoms are rearranged to form particles of oxygen dichloride
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 2 Assessments
13. Use the particle model to describe what happens when a spoonful of salt is put into water. [2 marks]
14. Describe how the strength of intermolecular forces affects the rate at which a liquid evaporates. [2
marks]
15. Explain why 22.4 litres of carbon dioxide, CO2, has a mass of 44 g, but 22.4 litres of oxygen, O2,
has a mass of 16 g. [2 marks]
16. Look at the table.
Explain why the values for expansion of a bar one metre long differ from material to material. [2 marks]
17. Describe how an aerosol spray can of paint works. [2 marks]
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 2 Assessments
18. Look at these ball-and-stick models.
Look at these diagrams and describe the differences between aluminium oxide and magnesium oxide. [4
marks]
19. Explain the relationship between the Brownian motion and kinetic theory. [4 marks]
© HarperCollinsPublishers 2014