Calculate number of bromide ions in 3 moles of mercury (II) bromide

Question

$\begin{array}{1 1} (a)\;3.507 \times 10^{23}\; ions\\ (b)\;3.507 \times 10^{20} \;ions \\ (c)\;1.507 \times 10^{19}\; ions \\(d)\;3.613 \times 10^{24}\; ions \end{array}$