Exam practice
Exam questions
Write your answer. Then open the mark scheme and tick each point you made.
- Question 1 of 101 mark
State what the word pure means in science.
Mark scheme
- Made of only one substance (accept: a single element or compound; nothing mixed in)
- Question 2 of 102 marks
A solid melts between 68 °C and 74 °C. Explain whether the solid is pure.
Mark scheme
- It is not pure (accept: it is a mixture)
- A pure substance melts at one fixed temperature (accept: this one melts over a range)
- Question 3 of 103 marks
Salt is stirred into water until it dissolves. Name the solute, the solvent and the solution.
Mark scheme
- Solute: salt
- Solvent: water
- Solution: salt solution (accept: salt water, salty water)
- Question 4 of 102 marks
5 g of sugar dissolves in 100 g of water. State the mass of the solution and give a reason.
Mark scheme
- 105 g
- Mass is conserved (accept: the sugar particles are still there, mixed in with the water particles)
- Question 5 of 101 mark
Describe what a saturated solution is.
Mark scheme
- A solution in which no more solute will dissolve (at that temperature)
- Question 6 of 102 marks
A student filters a mixture of sand and water. Name the residue and the filtrate.
Mark scheme
- Residue: sand
- Filtrate: water
- Question 7 of 102 marks
Explain why filtering does not separate salt from salt solution.
Mark scheme
- The salt is dissolved (accept: its particles are spread out among the water particles)
- The particles are small enough to pass through the holes in the filter paper
- Question 8 of 103 marks
Describe how distillation produces pure water from salt solution.
Mark scheme
- The solution is heated and the water evaporates (accept: boils)
- The water vapour is cooled in the condenser and condenses
- The salt is left behind in the flask
- Question 9 of 101 mark
Ink from a pen is tested by chromatography. Three coloured spots appear. State what this shows about the ink.
Mark scheme
- It is a mixture of three dyes (accept: three substances, three colours)
- Question 10 of 104 marks
Describe how to separate a mixture of sand, salt and water to get the sand and crystals of salt.
Mark scheme
- Filter the mixture
- The sand is left in the filter paper (accept: the sand is the residue)
- Heat the filtrate to evaporate the water
- Crystals of salt are left behind