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.

Most questions on exam papers have mark schemes that give key points that are given marks. The six-mark questions are marked differently: they use a levels-based mark scheme. This type of mark scheme is used because these questions are more open-ended. 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.

Answers are placed in three marking bands:

  • 1-2 marks for answers showing limited content and reasoning and with significant omissions
  • 3-4 marks for answers that give some relevant points, with linking and reasoning and with fewer omissions
  • 5-6 marks for answers that link most of the relevant points, with good links and reasoning. They will have few, if any, omissions.

Questions courtesy of Eduqas.

Sample question 1 - Foundation

Question

Group 1 compounds are all soluble in water.

Explain how you could prepare crystals of potassium nitrate from an acid and alkali of your choice.

Include a balanced symbol equation in your answer. [6 marks]

Your answer should include the following:

  • Reagents: nitric acid and potassium hydroxide (or potassium carbonate)
  • Use titration
  • Measure known volume of one reagent into conical flask using pipette, add indicator solution
  • Add other reagent steadily from burette whilst swirling flask
  • Add dropwise near to end-point
  • Record volume of reagent needed for colour change
  • Repeat reaction using identical volumes of both solutions but without indicator
  • Heat solution to reduce volume/evaporate, leave to crystallise
  • Titration used since both reagents are soluble in water so need to use titration to exactly neutralise acid and alkali
  • This way the solution will not contain unreacted acid or alkali which otherwise cannot be easily separated.
  • HNO3 + KOH → KNO3 + H2O or 2HNO3 + K2CO3 → 2KNO3 + H2O + CO2

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Sample question 2 - Higher

Question

Describe the similarities in the reactions of ethanoic acid and sulfuric acid with metals, carbonates and bases.

Describe and explain any differences observed. You should include relevant equations in your answer. [6 marks]

Your answer should include the following:

  • observations made when both acids react with metals, carbonates and bases
  • eg temperature rise, liberation of gas, time to dissolve
  • difference in rate of reaction
  • explanation in terms of strong/weak acid
  • salts formed
  • word/chemical equations

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