A-LevelChemistryChemical bondingOct/Nov 2010Paper 1 Q31 Mark
The table gives the radii, in pm, of some ions. [1 pm = 10⁻¹²m] ion radii Na⁺ 102 Mg²⁺ 72 Cs⁺ 167 Cl⁻ 181 O²⁻ 140 Caesium chloride, CsCl, has a different lattice structure from both sodium chloride, NaCl, and magnesium oxide, MgO. Which factor appears to determine the type of lattice for these three compounds?
Athe charge on the cation
Bthe ratio of the ionic charges
Cthe ratio of the ionic radii
Dthe sum of the ionic charges
✓ Correct Answer
The correct answer is C: the ratio of the ionic radii
📋 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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