Maths questions
Don't forget to take a ruler and calculator into the exam.
Maths questions 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:
- full marks are given for the right answer (but it is very important to show your working, so you can check your answer and so that, if you make a small slip, you can still get marks for your working)
- marks may be given for working, including substitution and rearrangement,
- 'errors carried forward' are worked through to give credit for later working.
Errors are carried forward if a later working depends on an earlier answer. You could still get marks 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. You may be asked to give units. This may earn you an additional mark, so don鈥檛 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:
- plot each point accurately
- draw a best fit straight line or curve, where appropriate
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:
- put the independent variable on the x-axis and the dependent variable on the y-axis
- choose even scales and make sure that the points cover at least half the given grid
- label the axes with their quantity and unit, eg time (s)
Learn maths skills with Dr Alex Lathbridge
Listen to the full series on 91热爆 Sounds.
Brush up on the maths you need for your exam - percentages, averages and converting units.
Sample question 1 - Foundation
Question
Calcium nitrate contains calcium ions and nitrate ions.
Calculate the relative formula mass of calcium nitrate, Ca(NO3)2.
(relative atomic masses: Ca = 40, N = 14, O = 16) [2 marks]
Edexcel question courtesy of Pearson Education Ltd.
40 + (2 脳 14) + (6 x 16) [1]
= 164 [1]
Sample question 2 - Foundation
Question
A sample of calcium bromide contains 0.2 g calcium and 0.8 g bromine by mass.
Calculate the empirical formula of calcium bromide.
(Relative atomic masses: Ca = 40, Br = 80) [3 marks]
Edexcel question courtesy of Pearson Education Ltd.
Divide mass by relative atomic mass [1]
\(\frac{0.2}{40}\) = 0.005 \(\frac{0.8}{80}\) = 0.01
Divide by the smallest number [1]
\(\frac{0.005}{0.005}\) = 1 \(\frac{0.01}{0.005}\) = 2
Empirical formula is CaBr2 [1]
Sample question 3 - Higher
Question
Calculate the mass of 0.25 mol of carbon dioxide, CO2.
(relative atomic masses: C = 12, O = 16) [2 marks]
This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
12 + (2 脳 16) = 44 [1]
(1 mol = 44 g)
0.25 脳 44 = 11 g [1]
Sample question 4 - Higher
Question
Two oxides of lead, R and S, were analysed. The empirical formula of oxide R was found to be PbO.
The results of the analysis of oxide S showed it contained 0.207 g of lead combined with 0.032 g of oxygen.
Show, by calculation, that the two oxides had different empirical formulae.
(relative atomic masses: O = 16, Pb = 207) [3 marks]
Edexcel question courtesy of Pearson Education Ltd.
Divide mass by relative atomic mass [1]
\(\frac{0.207}{207}\) = 0.001 \(\frac{0.032}{16}\) = 0.002
Divide by the smallest number [1] \(\frac{0.001}{0.001}\) = 1 \(\frac{0.002}{0.001}\) = 2
Empirical formula is PbO2, which is different to compound R [1]
More guides on this topic
- Equations and formulae - Edexcel
- Hazards and risks - Edexcel
- Atomic structure - Edexcel
- The periodic table - Edexcel
- Ionic compounds - Edexcel
- Simple molecular substances - Edexcel
- Giant covalent substances - Edexcel
- Metals and non-metals - Edexcel
- Chemistry calculations - Edexcel
- Mole calculations (higher) - Edexcel