A-LevelChemistryChemical periodicityFeb/Mar 2021Paper 1 Q351 Mark
A sample containing x mol of Al₂Cl₆ is dissolved in water to give solution W. In order to precipitate all of the aluminium as its hydroxide, y mol of sodium hydroxide are required. More of the alkali is added to re-dissolve the precipitate, giving solution Z. Which statements are correct? 1 the initial pH of solution W is below 7 2 y = 3x 3 Z contains x mol of aluminium
A1, 2 and 3 are correct
B1 and 2 only are correct
C2 and 3 only are correct
D1 only is correct
✓ Correct Answer
The correct answer is D: 1 only is correct
📋 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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