In Na 2 O 2 , the oxidation states respectively for Na and oxygen may be:

Let $\mathrm{x}$ be the oxidation state of $\mathrm{Na}$ in ${\mathrm{Na}}_2{\mathrm{O}}_2.$

${\mathrm{Na}}_2{\mathrm{O}}_2$ contains a peroxide linkage in which $\mathrm{O}$ has an

oxidation state of $-1.$

$\stackrel{\text{x}}{{\text{Na}}_2}\stackrel{-1}{{\text{O}}_2}$ or $2x+\; 2\; (-\; 1)\; =0$ or $x=\; +\; 1.$

 Thus, the oxidation state of sodium in ${\mathrm{Na}}_2{\mathrm{O}}_2$ is $+1.$