Let $N_{\beta}$ be the number of $\beta$ particles emitted by $1\;gram$ of $Na^{24}$ radioactive nuclei (half life = 15 hrs) in $7.5$ hours , $N_{\beta}$ is close to (Avogadro number

Question

$\begin{array}{1 1} 6.2 \times 10^{21} \\ 7.5 \times 10^{21} \\ 1.25 \times 10^{22} \\ 1.75 \times 10^{22} \end{array} $