A-LevelChemistryGroup 2Oct/Nov 2010Paper 1 Q171 Mark

Strontium metal can be obtained by the electrolysis of molten strontium bromide, SrBr₂, using the apparatus shown in the diagram. [Figure showing electrolysis apparatus for molten strontium bromide] Why is an atmosphere of argon used around the cathode?

Q: What topic does this question test?

This question tests Group 2 in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Athin film of a compound of strontium and argon forms on the surface protecting the freshly formed metal.

BThe argon keeps the strontium molten.

CThe argon stops the molten strontium rising too high in the tube.

DWithout the argon, strontium oxide would form in the air.

✓ Correct Answer

The correct answer is D: Without the argon, strontium oxide would form in the air.

📋 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 Group 2 in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2010 examination, Paper 1 Variant 2.

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