A-LevelChemistryChemical periodicityOct/Nov 2025Paper 1 Q171 Mark

Sodium and sulfur react together to form sodium sulfide, Na2S. How do the atomic radius and ionic radius of sodium compare with those of sulfur?

Q: What topic does this question test?

This question tests Chemical periodicity in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Asulfur is greater, sodium is greater

Bsulfur is greater, sulfur is greater

Csodium is greater, sodium is greater

Dsodium is greater, sulfur is greater

✓ Correct Answer

The correct answer is D: sodium is greater, sulfur is greater

📋 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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About This A-Level Chemistry Question

Topic

This multiple-choice question tests Chemical periodicity in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2025 examination, Paper 1 Variant 2.

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