# Question #37793

Well, $6.022 \times {10}^{23}$ $\text{magnesium atoms}$ constitute $1$ $\text{mole}$.
$\left(2.408 \times {10}^{23} {\text{ magnesium atoms")/(6.022xx10^23" magnesium atoms mol}}^{-} 1\right) = 0.400 \cdot m o l$