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 BBC Sounds.
How to write six-mark answers in your science GCSE exams.
Sample question 1 - Foundation
Question
Titanium, Ti, atomic number 22, is used to make the wings of some aeroplanes.
Predict four physical properties of titanium.
Explain why you make your predictions and relate the properties to the use of titanium in making aeroplane wings. [6 marks]
OCR Gateway Science, GCE Chemistry, Unit B742: Specimen paper (2012) Chemistry modules C4, C5, C6 (Foundation Tier)
Relevant points include:
- identification of titanium as a metal
- identification as a transition element using its position in the periodic table
- link that transition elements are metals
- physical properties - hard, good thermal conductor, good electrical conductor, lustrous, sonorous, high melting point, high boiling point, high tensile strength
Examples of relating properties to use in aeroplanes:
- idea of low density since it is used for an aeroplane and will require less force to lift
- idea of strong to be able to be used as a wing so can withstand forces
- idea of being malleable so it can be made into sheets
- also allow does not react with water/does not rust
- ignore solid/colour of metal/heavy/light not properties opposite to list above/magnetic
Sample question 2 - Foundation
Question
Jed is testing potassium chloride and some unknown compounds.
He does some tests.
These are the tests that Jed does on solutions of the compounds:
- a flame test
- adding sodium hydroxide solution
- adding silver nitrate solution
Look at his results.
| Compound | Flame colour | Adding sodium hydroxide solution | Adding silver nitrate solution |
| Potassium chloride | Lilac | No reaction | White solid made |
| A | Yellow | No reaction | White solid made |
| B | No colour | Green solid made | Cream solid made |
| Compound | Potassium chloride |
|---|---|
| Flame colour | Lilac |
| Adding sodium hydroxide solution | No reaction |
| Adding silver nitrate solution | White solid made |
| Compound | A |
|---|---|
| Flame colour | Yellow |
| Adding sodium hydroxide solution | No reaction |
| Adding silver nitrate solution | White solid made |
| Compound | B |
|---|---|
| Flame colour | No colour |
| Adding sodium hydroxide solution | Green solid made |
| Adding silver nitrate solution | Cream solid made |
Potassium chloride reacts with silver nitrate to make silver chloride and potassium nitrate.
Write a word equation for this reaction.
Identify the unknown compounds A and B and explain your answers. [6 marks]
OCR Gateway Science, GCE Chemistry, Unit B742: June 2016 Chemistry modules C4, C5, C6 (Foundation Tier)
Word equation:
- potassium chloride + silver nitrate → silver chloride + potassium nitrate
Mark awarded for correct formulae or mix of words and formulae.
Mark allowed for KCl + AgNO3 → AgCl + KNO3.
Compound A:
- compound A contains sodium (ions)
- compound A contains chloride (ions)
- compound A is sodium chloride
Reasons:
- because sodium gives a yellow flame test colour
- because chloride ions give a white precipitate with silver nitrate
Compound B:
- compound B contains iron(II) (ions)
- compound B contains bromide (ions)
- compound B is iron(II) bromide
Reasons:
- iron(II) (ions) give a green precipitate with sodium hydroxide
- bromide (ions) give a cream precipitate with silver nitrate - allow solid instead of precipitate
Sample question 3 - Higher
Question
This question is about group 1 elements such as sodium and rubidium.
Look at the table. It shows some information about the elements in group 1.
| Element | Atomic symbol | Atomic number | Melting point in °C | Density in g/cm3 | Atomic radius in pm |
| Lithium | Li | 3 | 181 | 0.53 | 152 |
| Sodium | Na | 11 | 98 | 0.97 | 182 |
| Potassium | K | 19 | 64 | 0.86 | 227 |
| Rubidium | Rb | 37 |
| Element | Lithium |
|---|---|
| Atomic symbol | Li |
| Atomic number | 3 |
| Melting point in °C | 181 |
| Density in g/cm3 | 0.53 |
| Atomic radius in pm | 152 |
| Element | Sodium |
|---|---|
| Atomic symbol | Na |
| Atomic number | 11 |
| Melting point in °C | 98 |
| Density in g/cm3 | 0.97 |
| Atomic radius in pm | 182 |
| Element | Potassium |
|---|---|
| Atomic symbol | K |
| Atomic number | 19 |
| Melting point in °C | 64 |
| Density in g/cm3 | 0.86 |
| Atomic radius in pm | 227 |
| Element | Rubidium |
|---|---|
| Atomic symbol | Rb |
| Atomic number | 37 |
| Melting point in °C | |
| Density in g/cm3 | |
| Atomic radius in pm |
Describe and explain the relationship between atomic radii and melting points of the elements in group 1.
Include in your answer predictions for the atomic radius and melting point of rubidium. [6 marks]
OCR Gateway Science, GCE Chemistry, Unit B742: Specimen paper (2012) Chemistry modules C4, C5, C6 (Higher Tier)
Relevant points include:
- melting point decreases as atomic radius increases
- melting point decreases because it is easier to overcome the metallic bond
- because strength of metallic bond decreases as atomic radius increases
- idea that metallic bond is the attraction between delocalised electrons and (closely packed) metal ions
- idea that atoms lose electrons more easily down group 1 because the attraction is weaker
- melting point of rubidium is any value between 30 to 50°C
- atomic radius of rubidium 272 to 295 pm
Sample question 4 - Higher
Question
Lithium, Li, is in group 1 of the periodic table.
Laura's teacher adds a small piece of lithium to a bowl of water.
The lithium reacts with the water. The lithium moves about on the surface of the water.
Laura sees bubbles of hydrogen being made.
The piece of lithium gets smaller and smaller until it has completely reacted. A solution of lithium hydroxide, LiOH, is made.
Caesium, Cs, is another element in group 1.
Predict, including a balanced symbol equation, how the reaction of caesium with water compares with the reaction of lithium with water. [6 marks]
OCR Gateway Science, GCE Chemistry, Unit B742/02: June 2013 Chemistry modules C4, C5, C6 (Higher Tier)
Relevant points include:
- 2Cs + 2H2O → 2CsOH + H2 OR 2Li + 2H2O → 2LiOH + H2
- faster reaction than with lithium/more reactive/more violent
- caesium + water → caesium hydroxide + hydrogen
- lithium + water → lithium hydroxide + hydrogen
- hydrogen made
- caesium hydroxide made
- bubbles/fizzes/floats/moves on the surface/gives a flame/gets smaller/forms a colourless solution/alkaline solution formed/explodes/caesium loses electrons more easily
