A-LevelChemistryEquilibriaOct/Nov 2021Paper 1 Q321 Mark
Four solutions, each of concentration 0.1 mol dm⁻³, were tested with a pH meter. The results are shown. solution | formula of acid or base | pH ---|---|--- acid 1 | CH3CO2H | 4 acid 2 | HNO3 | 1 base 1 | CH3NH2 | 11 base 2 | NaOH | 14 Which statements explain these results? 1 Acid 2 has a lower pH than acid 1 because it is more soluble. 2 Base 2 has a higher concentration of hydroxide ions in solution than base 1. 3 Acid 1 dissociates less than acid 2.
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 C: 2 and 3 only are 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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