A student observed the reactions when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid. Some observations are recorded in the table. sodium chloride with conc. H2SO4: colourless acidic gas formed sodium chloride with conc. H3PO4: colourless acidic gas formed sodium iodide with conc. H2SO4: purple vapour formed sodium iodide with conc. H3PO4: colourless acidic gas formed Which deduction can be made from these observations?
✓ Correct Answer
The correct answer is D: Concentrated sulfuric acid is a stronger oxidising agent than iodine.
📋 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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