Six-mark questions
Six-mark questions are extended open response questions. These require longer answers than the structured questions that have fewer marks. It is wise to plan your answer first by making some notes. This will help you to include all the key points.
To gain full marks, you need to:
- support explanations using scientific knowledge and understanding
- use appropriate scientific words
- write clearly and link ideas in a logical way
- maintain a sustained line of reasoning
Writing six-mark answers with Dr Alex Lathbridge
Listen to the full series on BBC Sounds.
How to write six-mark answers in your science GCSE exams.
Six-mark questions often use these command words:
- 'Describe' means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.
- 'Explain' means you need to make something clear, or state the reasons for something happening.
- 'Compare' means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y, and give a comparison. Do not just write about X only or Y only.
- 'Evaluate' means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.
Six-mark questions may be synoptic questions, which 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.
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 sentences, linking them logically and clearly.
Sample question 1 - Foundation
Question
A student is provided with a sample of a gas and asked to identify it. He knows that the gas is either chlorine, oxygen, carbon dioxide or hydrogen. Describe how the student should analyse the gas in order to identify it. Describe the tests that he should do, and how he should interpret his observations. [6 marks]
This question is AQA material which is reproduced by permission of AQA.
The following are valid 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.
- split the gas into four samples
- test one sample with a burning splint
- a squeaky pop sound would identify hydrogen
- test another sample with damp litmus paper
- if it turns white then the gas is chlorine
- test another sample with a glowing splint
- if the splint relights then the gas is oxygen
- test the final sample with limewater
- if the limewater goes cloudy then the gas is carbon dioxide
[6]
Sample question 2 - Foundation
Question
A coloulrless solution contains potassium ions, but the identity of the negatively charged ion is a mystery. Describe a series of tests which would enable you to deduce if the negatively charged ion was iodide, carbonate, sulfate, chloride or bromide. [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 valid 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.
- take small samples from the solution for the following tests
- add some dilute acid to one of the samples
- if it fizzes and the gas turns limewater cloudy then the carbonate ion is present
- add some dilute barium chloride solution to one of the samples
- if a white precipitate forms then sulfate ions are present
- add some dilute silver nitrate to one of the samples
- if a white precipitate forms then the chloride ion is present
- if a cream precipitate forms then the bromide ion is present
- if a yellow precipitate forms then the iodide ion is present
[6]
Sample question 3 - Higher
Question
A waterproof pen has ink which is insoluble in water. A student wants to investigate which pigments are used to make the ink. Describe how she should use paper chromatography to identify how many pigments are in the ink. [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 valid 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.
- draw a horizontal line in pencil near the bottom of the piece of chromatography paper
- place a spot of the ink from the pen on the pencil line
- place the piece of paper into a beaker so that it doesn't touch the sides, eg hang it from above
- add a small amount of a suitable solvent (not water)...
- ...so that the level of the solvent is below the pencil line/spot
- allow the solvent to rise up the paper
- count the number of spots/colours on the chromatogram
[6]
Sample question 4 - Higher
Question
Devise a series of experiments to distinguish between the following compounds.
- sodium chloride
- sodium carbonate
- potassium chloride
- potassium iodide
- potassium sulfate
Write your answer in a logical sequence of steps and include the expected observations and how you would interpret your observations. [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 valid 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.
- first, do a flame test
- two compounds will give a yellow colour which identifies them as the sodium compounds
- three compounds will give a lilac colour, which identifies them as the potassium compounds
- then, test with dilute nitric acid, followed by silver nitrate...
- the sodium carbonate will fizz, and the gas will turn limewater cloudy
- the sodium chloride and potassium chloride will produce a white precipitate
- the potassium iodide will produce a yellow precipitate
- the potassium sulfate will not produce a precipitate
- (the potassium sulfate will produce a precipitate with barium chloride)
