A-LevelChemistryGroup 17Feb/Mar 2025Paper 2 Q315 Marks
The halogens chlorine, bromine and iodine show trends in chemical and physical properties down the group. Table 3.1 shows some properties of chlorine, bromine and iodine. Table 3.1 property | chlorine | bromine | iodine ---|---|---|--- colour and state at room temperature | green gas | | bond energy/kJ mol–1 | 242 | 193 | 151 electronegativity | 3.0 | 2.8 | 2.5 formula of sodium halide | NaCl | NaBr | NaI
📋 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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