A-LevelChemistryGroup 17Feb/Mar 2025Paper 1 Q191 Mark
U, V and W represent different halogens. The table shows the results of nine experiments in which aqueous solutions of U2, V2 and W2 were separately added to separate aqueous solutions containing U⁻, V⁻ and W⁻ ions. U⁻(aq) V⁻(aq) W⁻(aq) U2(aq) no reaction no reaction no reaction V2(aq) U2 formed no reaction W2 formed W2(aq) U2 formed no reaction no reaction Which row contains the ions U⁻, V⁻ and W⁻ in order of their decreasing strength as reducing agents?
AU⁻ V⁻ W⁻
BU⁻ W⁻ V⁻
CV⁻ W⁻ U⁻
DW⁻ U⁻ V⁻
✓ Correct Answer
The correct answer is B: U⁻ W⁻ V⁻
📋 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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