(a)[2]
Calculate the number of protons and the number of neutrons in a nucleus of $X$.
(b)[1]
Explain why the kinetic energy given to the $\alpha$-particle is smaller than the $5.5\,\text{MeV}$ of energy released in the decay.
(c(i))[2]
A sample of $X$ is used to generate a beam of $\alpha$-particles in a vacuum. The number of $\alpha$-particles passing a fixed point in the beam in $30\,\text{s}$ is $6.9 \times 10^{11}$. Calculate the mean current produced by the beam of $\alpha$-particles.
(c(ii))[2]
Determine the total power, in $\text{W}$, produced by the decay of $6.9 \times 10^{11}$ nuclei of $X$ in $30\,\text{s}$.