A-LevelChemistryElectrochemistryMay/June 2013Paper 1 Q11 Mark

During the electrolysis of molten aluminium oxide to produce aluminium, using carbon electrodes, two consecutive reactions occur at the anode, each producing a different gas. How does the oxidation number of oxygen change in these reactions?

Q: What topic does this question test?

This question tests Electrochemistry in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Adecreases by 2, then increases by 2

Bincreases by 2, then decreases by 2

Cincreases by 2, then decreases by 4

Dno change, then decreases by 2

✓ Correct Answer

The correct answer is B: increases by 2, then decreases by 2

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Chemistry Question

Topic

This multiple-choice question tests Electrochemistry in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry May/June 2013 examination, Paper 1 Variant 2.

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