A-LevelChemistryChemical periodicityFeb/Mar 2022Paper 1 Q171 Mark
A student investigated the chloride of a Period 3 element. This is what the student wrote down as a record. "The compound was a white crystalline solid. It dissolved easily in water to give a solution of pH 12. When placed in a test-tube and heated in a roaring Bunsen flame, the compound melted after several minutes heating." What can be deduced from this record?
AAt least one of the recorded observations is incorrect.
BThe compound was magnesium chloride, MgCl₂.
CThe compound was phosphorus pentachloride, PCl₅.
DThe compound was sodium chloride, NaCl.
✓ Correct Answer
The correct answer is A: At least one of the recorded observations is incorrect.
📋 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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