(a)[1]
Define the activity of a radioactive sample.
(b)[3]
Explain why the activity of a radioactive sample varies exponentially with time.
(c(i))[2]
Determine the decay constant, in $\text{min}^{-1}$, for the radioactive isotope.
(c(ii))[1]
Use your answer in c(i) to determine the half-life, in min, of the radioactive isotope.
(c(iii))[3]
On Fig. 9.1, sketch how the activity $A$ of the sample varies with $t$ for values of $t$ between $t = 0$ and $t = 24\,\text{min}$.