(a(i))[2]
Suggest how the nucleus of a stable isotope of strontium is different from the nucleus of strontium-90. Explain your answer.
(a(ii))[2]
Complete the nuclide equation for the decay of strontium-90 into yttrium. $^{90}_{38}\text{Sr} \rightarrow \; \; Y + \beta$
(a(iii))[2]
Explain why scientists keep their exposure time to radioactive strontium as short as possible.
(b(i))[3]
Use Fig. 9.1 to work out the half-life of yttrium. Show your working.
(b(ii))[1]
Explain the difference between the count rate in Table 9.1 and the yttrium count rate shown on the graph in Fig. 9.1.