A-LevelChemistryGroup 17Feb/Mar 2023Paper 1 Q181 Mark
Powder P is a mixture containing two of AgCl, AgBr or AgI. P is shaken with dilute aqueous ammonia. A yellow solid, Q, remains. The mixture is filtered and Q is washed and dried. The filtrate is collected and treated with aqueous nitric acid to produce a white precipitate, R, which is filtered off, washed and dried. Q and R are warmed separately with concentrated sulfuric acid, H2SO4. Which observations are made? [Table with columns "Q + concentrated H2SO4", "R + concentrated H2SO4"]
Aviolet fumes, orange fumes
Bviolet fumes, steamy fumes
Csteamy fumes, violet fumes
Dorange fumes, steamy fumes
✓ Correct Answer
The correct answer is B: violet fumes, steamy fumes
📋 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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