Answer
3.7
Work Step by Step
Decay constant $k=\frac{0.693}{t_{1/2}}=\frac{0.693}{3.0\times10^{5}\times365\times24\times60\,min}=4.395\times10^{-12}\,min^{-1}$
Number of moles $n=\frac{\text{mass in grams}}{\text{molar mass}}=\frac{5.0\times10^{-3}\,g}{36\,g/mol}=1.3889\times10^{-4}\,mol$
Number of particles $N=n\times\text{Avogadro number}$
$=1.3889\times10^{-4}\times 6.022\times10^{23}=8.364\times10^{19}$
Decay rate=$kN=4.395\times10^{-12}\,min^{-1}\times8.364\times10^{19}=3.7\text{ emissions per minute}$
