Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical 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’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:

- 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)

- Question
Copper sulfate solution was electrolysed for five minutes using copper electrodes.

The table shows the mass of the anode and of the cathode before electrolysis and after electrolysis.

Anode Cathode Mass of electrode before electrolysis 1.16 g 1.28 g Mass of electrode after electrolysis 0.85 g 1.57 g Calculate the mass of copper deposited.

**[2 marks]***Edexcel question courtesy of Pearson Education Ltd.*- Copper is deposited on the cathode, therefore mass deposited = 1.57 - 1.28 [1]
- = 0.29 (g) [1]

- Question
A student made an insoluble salt. He used the method below:

- Mix together silver nitrate and sodium chloride solutions
- Filter the mixture to separate the precipitate from the solution
- Use distilled water to wash the precipitate
- Place the washed precipitate in a warm place to dry

The student measured the mass of the wet precipitate.

He measured the mass again when it was dry.

His results are in the table.

Mass in g Wet Precipitate 2.21 Dry Precipitate 1.97 Calculate the mass of water that evaporated from the wet precipitate during drying.

**[1 mark]***This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.*Mass of water = mass of wet precipitate - mass of dry precipitate

Mass of water = 2.21 g - 1.97 g

0.24 g [1]

- Question
Copper is purified by the electrolysis of copper sulfate solution using an impure copper anode and a pure copper cathode.

Write the half equation for the formation of a copper atom from a copper ion.

**[2 marks]***Edexcel question courtesy of Pearson Education Ltd.*Cu

^{2+}+ 2e^{-}→ Cu- All species [ions, electrons, atoms]. [1]
- Correctly balanced. [1]

- Question
Water is added to a sample of dilute hydrochloric acid. The concentration of hydrogen ions decreases by a factor of 100.

Predict the effect on the pH of the solution.

**[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.*The pH increases [1] by 2. [1]