Answer
18.0 g $O_{2}$
Work Step by Step
$2KClO_{3}$ -> $2KCl+3O_{2}$
mass of $O_{2}$ = $\frac{(46.0g2KClO_{3})\times(3molO_{2})\times(32gO_{2})}{(122.5g2KClO_{3})\times(2mol2KClO_{3})\times(1molO_{2})}$
$\approx$ 18.0244898 g $O_{2}$
= 18.0 g $O_{2}$
