Question:
Find the oxidation state of sodium in $\mathrm{Na}_{2} \mathrm{O}_{2}$.
Solution:
Let the oxidation state of Na be x. The oxidation state of oxygen, in case of peroxides, is –1.
Therefore,
$2(x)+2(-1)=0$
$2 x-2=0$
$2 x=2$
$x=+1$
Therefore, the oxidation sate of sodium is +1.