(a)[2]
State which quantities are conserved in a nuclear reaction apart from momentum.
(b(i))[1]
A uranium-238 nucleus initially at rest decays into a thorium-234 nucleus by emitting an $\alpha$-particle. The kinetic energy of the $\alpha$-particle is $6.69\times10^{-13}\,\text{J}$. Show that the kinetic energy $E_k$ of a mass $m$ is related to its momentum $p$ by the equation $$E_k = \frac{p^2}{2m}.$$
(b(ii))[3]
Use conservation of momentum to find the kinetic energy, in keV, of the thorium nucleus.