A-LevelPhysicsParticle physics9702/12 · May/June 2021 · 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?

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

A: The number of down quarks decreases by one.

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Topic: Particle physics, A-Level Physics (syllabus 9702). Multiple choice, 1 mark.
Source: A-Level Physics, May/June 2021 Paper 1 Variant 2, question 40.

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