(a)[2]
State what is meant by the term isotopes.
(b)[3]
Calculate the decay probability per second for a strontium-89 nucleus.
(c(i))[2]
A laboratory prepares a strontium-89 source. Its activity is measured 21 days after preparation and is found to be $7.4 \times 10^{6}\,\text{Bq}$. Determine the activity of the strontium-89 source when it was first prepared.
(c(ii))[2]
Calculate the mass of strontium-89.