A-LevelPhysicsParticle physicsMay/June 2021Paper 1 Q401 Mark

In β⁻ decay, a neutron inside a nucleus changes to a proton. Which statement describes the quark composition of the nucleus during the decay?

Q: What topic does this question test?

This question tests Particle physics in A-Level Physics (syllabus code 9702). It is worth 1 mark.

AThe number of down quarks decreases by one.

BThe number of down quarks increases by one.

CThe number of down quarks stays the same.

DThe number of up quarks stays the same.

✓ Correct Answer

The correct answer is A: The number of down quarks decreases by one.

📋 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 Physics Question

Topic

This multiple-choice question tests Particle physics in A-Level Physics (syllabus code 9702). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Physics May/June 2021 examination, Paper 1 Variant 2.

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