An excited nucleus is claimed to decay in two sequential steps: 1

PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation

Problem

An excited nucleus 1840Ar∗^{40}_{18}\text{Ar}^{*} is claimed to decay in two sequential steps: 1. 1840Ar∗→ 1940K+e−+νˉe^{40}_{18}\text{Ar}^{*} \to\, ^{40}_{19}\text{K} + e^{-} + \bar{\nu}_e 2. 1940K→ 1840Ar+e++νe^{40}_{19}\text{K} \to\, ^{40}_{18}\text{Ar} + e^{+} + \nu_e Which statement about the overall transformation (from the initial 1840Ar∗^{40}_{18}\text{Ar}^{*} to the final 1840Ar^{40}_{18}\text{Ar} plus emitted particles) is correct? (a) Charge is conserved, but lepton number is not, so the overall process is forbidden. (b) Charge, nucleon number, and lepton number are all conserved, so the overall process is allowed. (c) Lepton number is conserved, but charge is not, so the overall process is forbidden. (d) Charge and lepton number are both conserved, but nucleon number is violated, so the overall process is forbidden.

Related theory

Browse the problem library