Remember that you will need to take a ruler and calculator into the exam.
Questions that test mathematical skills will often start with command words like 'Calculate...' 'Determine...', 'Estimate...' and 'Measure...'. They will then include blank space for you to show your working.
When an answer to a maths question is marked:
An 'error carried forward' means that, in questions with more than one part, your answer to a later question part will be marked according to your answer for the earlier part, even if you got this wrong. So, you could still get full marks in the later answer if your working is correct but you use the incorrect earlier answer.
If your answer has many decimal places or figures, make sure you give it to an appropriate number of decimal places or significant figures. If in doubt, match the number of decimal places or significant figures to the data given in the question.
You may be asked to give units. This may earn you an additional mark, so don’t forget to check whether you need to do this.
Maths questions might ask you to plot or complete a graph or table. When you draw a graph, make sure you:
You may be given a grid with axes labelled and scales already given. Sometimes you may be given an empty grid for you to supply your own axes. When you do this:
Label the axes with their quantity and unit, eg time (s).
Questions courtesy of Eduqas.
Sodium chlorate, NaClO3, is used to bleach paper.
Calculate the relative formula mass (Mr) of sodium chlorate. [2 marks]
When 36 g of water is broken down into its elements, 4 g of hydrogen is produced. Calculate the mass of oxygen produced. [1 mark]
32 g 
The overall equation for the extraction of aluminium is as follows.
2Al2O3 → 4Al + 3O2
a) Calculate how many tonnes of aluminium can be obtained from 2040 tonnes of aluminium oxide. [3 marks]
b) Calculate the volume of oxygen in m3 that could be formed from 2040 tonnes of aluminium oxide. The volume of 1 mol of gas at room temperature and pressure is 0.024 m3. [3 marks]
a)Mr Al2O3 = 102 
Mass ratio 204 : 108 
Answer = 1080 tonnes 
b) Mass ratio 2040 : 960 
Number of moles oxygen = (960 × 106) ÷ 32 
Volume = (3 × 107) × 0.024 = 7.2 × 105 m3 
Sulfur dioxide can be produced by heating sulfide ores such as iron(II) sulfide, FeS2, in oxygen.
4FeS2(s) + 11O2(g) → 2Fe2O3(s) + 8SO2(g)
a) Calculate the number of moles in 176 tonnes of SO2.
1 tonne = 1 × 106 g [3 marks]
b) Use your answer to part (a) to calculate the minimum mass of iron sulfide, FeS2, required to produce 176 tonnes of SO2. [2 marks]
a)Mr(SO2) = 64 
Indication of 176/64 or 2.75 
2.75 × 106 mol 
b) 1.375 × 106 mol or indication that mass in grams multiplied by 120 
165 tonnes