A-LevelChemistryGroup 2May/June 2023Paper 1 Q211 Mark
Solutions P and Q each contain a different Group 2 ion at the same concentration. One contains Mg²⁺ and the other contains Ba²⁺. Tests are carried out on separate 5 cm³ samples of P and Q. test 1: add 1 cm³ of 0.1 mol dm⁻³ Na₂SO₄(aq) test 2: add 1 cm³ of 0.1 mol dm⁻³ NaOH(aq) What are the results of these tests?
Amore precipitate with Ba²⁺ more precipitate with Ba²⁺
Bmore precipitate with Ba²⁺ more precipitate with Mg²⁺
Cmore precipitate with Mg²⁺ more precipitate with Ba²⁺
Dmore precipitate with Mg²⁺ more precipitate with Mg²⁺
✓ Correct Answer
The correct answer is B: more precipitate with Ba²⁺ more precipitate with Mg²⁺
📋 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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