The decomposition of the smog component peroxyacetyl nitrate $(PAN)$ follows a first-order reaction into peroxyacetyl radical and $NO_{2(g)}$,with a half-life of $32 \ min$.
$CH_3COONO_2 \to CH_3COO^{\bullet} + NO_2$
If the initial concentration of $PAN$ in an air sample is $5.0 \times 10^{14} \ molecules/L$,what will be the concentration after $1.5 \ hr$?

• A
  $4.6 \times 10^{12} \ molecules/L$
• B
  $3.56 \times 10^{13} \ molecules/L$
• C
  $7.1 \times 10^{13} \ molecules/L$
• D
  $2.86 \times 10^{6} \ molecules/L$