Six-mark questions
Six-mark questions are extended open response questions. These require longer answers than the structured questions. It is wise to plan your answer rather than rushing straight into it, otherwise you may stray away from the key points.
To gain full marks, you need to:
- support explanations using scientific knowledge and understanding
- use appropriate scientific words and terms
- write clearly and link ideas in a logical way
- maintain a sustained line of reasoning, rather than getting lost or bogged down
Six-mark questions often use these command words:
- 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. These questions 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 full sentences, linking them logically and clearly.
Edexcel questions courtesy of Pearson Education Ltd.
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
Two elements in group 1 of the periodic table are lithium and sodium.
Very small pieces of lithium and sodium were reacted separately with water.
Describe the similarities and differences in what is seen and in the products of the reactions. [6 marks]
Your answer should include the following:
Similarities:
Both:
- float/on the surface
- move around
- effervesce/bubble/fizz
- decrease in size/disappear/dissolve
- produce hydrogen/H2
- produce (metal) hydroxide/LiOH and NaOH
- produce alkaline solution/solution with pH greater than 7/add named indicator to the solution and correct colour change
- correct products shown in equations
Differences:
- sodium more vigorous/more effervescence/moves faster
- melts
- forms ball/sphere
- produces a flame/catches fire/sparks
[6]
Sample question 2 - Foundation
Question
Sodium reacts with chlorine (which is toxic) to form sodium chloride.
Describe how the reaction can be carried out, explaining what happens when a sodium atom reacts with a chlorine atom. [6 marks]
Your answer should include the following:
Practical procedure:
- burning (sodium) placed in chlorine in gas jar/conical flask/tall beaker
- white fumes/sodium chloride forms as a solid
Safety:
- done in fume cupboard
- because chlorine is toxic
Theoretical:
- sodium atoms lose electrons
- lose one electron
- forms sodium ions
- Na+/with positive charge
- chlorine atoms gain electrons
- one electron gained
- forms chloride ions
- Cl-/with negative charge
- forms NaCl
- attraction between oppositely charged ions
- ionic bond
[6]
Sample question 3 - Higher
Question
The elements chlorine, bromine and iodine are part of group 7 in the periodic table.
The order of reactivity of chlorine, bromine and iodine can be determined by carrying out displacement reactions.
Explain how displacement reactions can be used to show the reactivity of these three elements. [6 marks]
Order of reactivity - chlorine > bromine > iodine.
The order of reactivity supported by suitable experiments from:
- add (aqueous) chlorine to a solution of potassium bromide
- the solution turns orange/yellow
- bromine is produced/Cl2 + 2KBr → Br2 + 2KCl/Cl2 + 2Br- → Br2 + 2Cl-
- so chlorine is more reactive than/displaces bromine/oxidises bromide ions
- add (aqueous) bromine to a solution of potassium iodide
- the solution turns yellow/red/ brown
- iodine is produced/Br2 + 2KI → I2 + 2KBr/Br2 + 2I- → I2 + 2Br-
- so bromine is more reactive than/displaces iodine/ oxidises iodide ions
- add (aqueous) chlorine to a solution of potassium iodide
- the solution turns yellow/red/brown
- iodine is produced/Cl2 + 2KI → I2 + 2KCl/Cl2 + 2I- → I2 + 2Cl-
- so chlorine is more reactive than/displaces iodine/oxidises iodide ions.
[6]
Sample question 4 - Higher
Question
Group 1 of the periodic table contains the alkali metals lithium, sodium and potassium.
The alkali metals show a pattern in their reactivity with water.
This pattern is shown when small pieces of lithium, sodium and potassium are added separately to water.
Describe the reactions and what would be seen and explain the pattern in reactivity.
You may include equations as part of your answer. [6 marks]
Your answer should include the following:
Description:
- effervescence/fizzing/bubbles
- float/on surface
- moves (around)
- produce hydrogen (may be shown in word or balanced equation)
- an alkaline/metal hydroxide solution (may be shown in word or balanced equation)
- gets smaller/disappears/dissolves
- reactivity increases with increasing atomic number/down the group/potassium effervesces more than sodium and lithium/potassium moves faster than sodium or lithium
- sodium and potassium melt/form a (silver-coloured) ball
- hydrogen burns when potassium/sodium react
- potassium gives a lilac flame/sodium gives a yellow flame
- universal indicator added to water turns blue/purple
Explanation:
- (group 1 metals) react by losing one electron
- electron is more easily lost with increasing atomic number/down the group
- electron/outer shell is further away from nucleus/atomic radius increases/there are more electron shells with increasing atomic number/down the group
[6]
