A neutron-rich nucleus ᴬZX undergoes β⁻-decay. The parent nucleus is initially at rest. Which reaction correctly shows the change of the nucleus and the leptons required for conservation of charge, energy and lepton number?
Options

Question

A neutron-rich nucleus ᴬZX undergoes β⁻-decay. The parent nucleus is initially at rest. Which reaction correctly shows the change of the nucleus and the leptons required for conservation of charge, energy and lepton number?

Options

G1 Physics · Accepted Answer

In β⁻-decay, a neutron inside the nucleus changes into a proton: n → p + e⁻ + ν̄ₑ. The total number of nucleons does not change, so mass number A remains the same. Because one neutron becomes one proton, atomic number increases by 1: Z → Z+1. Therefore the nuclear reaction is ᴬZX → ᴬ(Z+1)Y + e⁻ + ν̄ₑ. Correct option: A.