Physics 9702 · AS & A Level · Atoms, nuclei and radiation

Atoms, nuclei and radiation — practice question

(a)[2]

The nuclide $^{14}_{6}\text{C}$ (carbon-14) is unstable and undergoes $\beta^-$ decay, releasing a high-energy electron and an antineutrino to produce a new nuclide $X$. The decay equation is shown as $^{14}_{6}\text{C} \rightarrow \,\dots\dots\, X + \,\dots\dots\, e^- + {}^{0}_{0}\bar{\nu}$. Complete the equation.

(b(i))[1]

State the equation for $\beta^-$ decay using the fundamental particles involved.

(b(ii))[1]

Use your equation from (b)(i) to show that charge is conserved in $\beta^-$ decay.

(c(i))[1]

Neutrinos were first suggested to exist more than 20 years before they were directly detected, so as to account for a specific experimental observation in $\beta$-decay. State one observation about $\beta$-decay that is explained by neutrinos.

(c(ii))[1]

Suggest how the existence of neutrinos accounts for the observation in (c)(i).

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct nuclide shown as $^{14}_{7}X$

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