A-LevelChemistryGroup 17Feb/Mar 2020Paper 1 Q141 Mark

Hot aqueous sodium hydroxide reacts with chlorine. 6NaOH(aq) + 3Cl2(g) → 5NaCl(aq) + NaClO3(aq) + 3H2O(l) Which statement is correct?

Q: What topic does this question test?

This question tests Group 17 in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

AThe oxidation numbers of chlorine and hydrogen both change in the reaction.

BThe oxidation numbers of chlorine in the products are -1 and +1.

CIf the aqueous sodium hydroxide is cold the reaction produces NaClO instead of NaClO3.

DSodium undergoes disproportionation in this reaction.

✓ Correct Answer

The correct answer is C: If the aqueous sodium hydroxide is cold the reaction produces NaClO instead of NaClO3.

📋 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 Group 17 in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Feb/Mar 2020 examination, Paper 1 Variant 2.

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