We know that 1 mole contain $6.023 × 10^{23}$ molecules
So, $3.56 × 10^{–12}$ molecule will be equivalent to
$1$ mole $= 6.023 × 10^{23}$ molecule
$\begin{aligned} & 3.56 \times 10^{-12} \text { molecule }=\frac{1 \mathrm{Mole} \times 356 \times 10^{-12}}{6.023 \times 10^{-23}} \\ \end{aligned}$