(a(i))[1]
Radioactive decay is both random and spontaneous. State the meaning of random.
(a(ii))[1]
Radioactive decay is both random and spontaneous. State the meaning of spontaneous.
(b)
A sample of radioactive substance contains atoms of an unstable nuclide $X$. The activity from the atoms of $X$ is $A$. The change of $\ln A$ with time $t$ is shown in Fig. 12.1.
(b(i))[3]
Use Fig. 12.1 to find the half-life, in minutes, of nuclide X.
(b(ii))[3]
At time $t = 0$, the mass of the atoms of X in the sample is $5.66 \times 10^{-7}\,\text{kg}$. Find the nucleon number of X.