# Question #d90e9

$1.5 \cdot {10}^{23}$ molecules
.25 mol O $\frac{6.022 \cdot {10}^{23}}{1 m o l O}$ = $1.5 \cdot {10}^{23}$ molucules
When asked to find the number of molecules of any element, you multiply the number of moles by Avogadro's number, $6.022 \cdot {10}^{23}$.