Six mark questions
Six mark questions are extended open response questions. These require longer answers than the structured questions with fewer marks. It is wise to plan your answer rather than rushing straight into it, otherwise you may stray away from the key points.
Six mark questions are marked using a levels-based mark scheme because they are open ended. To gain full marks, you need to:
- support explanations using scientific knowledge and understanding
- use appropriate scientific words and terms
- write clearly, linking ideas in a logical way
- maintain a sustained line of reasoning, rather than getting lost or bogged down
You are likely to see command words such as:
- describe - you need to give an account but no reason
- explain - you must give reasons or explanations
- devise - you must plan or invent a procedure using your scientific knowledge and understanding
- evaluate - you must review information, including identifying strengths and weaknesses, and make a supported conclusion
Six mark questions may be synoptic questions. This means they bring together ideas from two or more topics. For example, a question about fertilisers could include ideas about covalent substances, acids and alkalis, chemical calculations, and effects on the environment.
Remember that the topics covered in the first paper are assumed knowledge for the second paper, so questions in the second paper may need knowledge and understanding of those topics too.
The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain six marks, but you do need to write in full sentences, linking them logically and clearly.
Writing six-mark answers with Dr Alex Lathbridge
Listen to the full series on 大象传媒 Sounds.
How to write six-mark answers in your science GCSE exams.
Sample question 1 - Foundation
Question
Describe the experimental procedure to carry out a titration to find the exact volume of sulfuric acid needed to neutralise 25.0 cm3 of sodium hydroxide solution. [6 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 following are vaild points that could be included in your answer. It is important that you do not bullet point your answer but write your sentences in full.
- rinse pipette with alkali and burette with acid
- measure alkali using a pipette into suitable container, eg flask/beaker, and place flask on a white tile
- add a few drops of indicator/suitable named indicator, eg methyl orange/phenolphthalein
- fill burette with acid and read volume of acid in burette
- add acid from burette to the flask slowly, swirling the flask until indicator just changes colour
- methyl orange: yellow to orange at end point
- phenolphthalein: pink to colourless at end point
- read volume of acid in burette at end of titration
- repeat experiment until concordant results
- calculate mean titre
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Sample question 2 - Higher
Question
Methane can be produced in this reaction
carbon dioxide + hydrogen 鈬 methane + water
CO2(g) + 4H2(g) 鈬 CH4(g) + 2H2O(l)
The table shows the percentage yield of methane in the equilibrium mixture under different conditions of temperature (in atmospheres) and pressure (掳C).
| 100 atmospheres | 200 atmospheres | 300 atmospheres | 400 atmospheres | |
| 300 掳C | 35% | 52% | 65% | 80% |
| 600 掳C | 30% | 46% | 58% | 74% |
| 900 掳C | 23% | 37% | 47% | 62% |
| 1200 掳C | 14% | 25% | 36% | 48% |
| 300 掳C | |
|---|---|
| 100 atmospheres | 35% |
| 200 atmospheres | 52% |
| 300 atmospheres | 65% |
| 400 atmospheres | 80% |
| 600 掳C | |
|---|---|
| 100 atmospheres | 30% |
| 200 atmospheres | 46% |
| 300 atmospheres | 58% |
| 400 atmospheres | 74% |
| 900 掳C | |
|---|---|
| 100 atmospheres | 23% |
| 200 atmospheres | 37% |
| 300 atmospheres | 47% |
| 400 atmospheres | 62% |
| 1200 掳C | |
|---|---|
| 100 atmospheres | 14% |
| 200 atmospheres | 25% |
| 300 atmospheres | 36% |
| 400 atmospheres | 48% |
A chemist predicts that the reaction between carbon dioxide and hydrogen is endothermic, and that it involves a decrease in the volume of gases.
Describe and explain whether the chemist鈥檚 predictions are supported by the reaction and results in the table. [6 marks]
OCR Gateway Science, GCE Chemistry, Paper J248, 2016 - Higher.
The following are vaild points that could be included in your answer. It is important that you do not bullet point your answer but write your sentences in full.
Temperature, pressure and yield:
- as temperature increases in an exothermic reaction, the position of equilibrium shifts to the left
- as pressure increases, the position of equilibrium shifts to the side with the fewest moles of gas
- decreasing the temperature favours the exothermic reaction
Analysing information in the table:
- as temperature increases, the percentage yield decreases
- as temperature increases, the position of equilibrium moves to the left
- as the pressure increases, the percentage yield increases
- as the pressure increases, the position of equilibrium moves to the right
Judgement/conclusion:
- the prediction is not supported - the reaction must be exothermic, because the position of equilibrium moves to the left as temperature increases
- the prediction is supported in terms of the moles of gas - as pressure increases, the position of equilibrium moves to the right
- the prediction is supported - as the pressure increases, the percentage yield increases
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