Physics 9702 · AS & A Level · Atoms, nuclei and radiation
Atoms, nuclei and radiation — practice question
A nuclear reaction involving two helium nuclei yields a second helium isotope, two protons and $13.8\,\text{MeV}$ of energy. The reaction is shown by the equation:
$^{3}_{2}\text{He} + {}^{3}_{2}\text{He} \rightarrow {}^{\;\;\; }_{\;\;\; }\text{He} + 2\,{}^{\;\;\; }_{\;\;\; }\text{p} + 13.8\,\text{MeV}$.
(a)[2]
Complete nuclear equation.
(b)[2]
Using this reaction, explain what is meant by isotope.
(c)[2]
State which quantities are conserved in this nuclear reaction.
(d(i))[1]
Radiation is emitted in this nuclear reaction. State a possible type of radiation that may be emitted.
(d(ii))[1]
Explain why this radiation has less energy than the $13.8\,\text{MeV}$ stated in the equation.
(e)[2]
Calculate the minimum number of these reactions per second required to give power of $60\,\text{W}$.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “With correct $A$ numbers $(4,1)$, $^3_2\mathrm{He} + ^3_2\mathrm{He} \rightarrow ^4_2\mathrm{He} + ^1_1\mathrm{p} + Q$” …