The sum of oxidation number of all atoms in $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}$ ion is
The sum of oxidation number of all atoms in $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}$ ion is
$+2$
$+5$
$-2$
$+7$
Solution
The sum of the oxidation numbers of all atoms in a polyatomic ion is equal to the charge of the ion. For example, in the ion $\mathrm{S}_2 \mathrm{O}_3^{2-}$, the sum of the oxidation numbers of sulfur and oxygen atoms is equal to the charge of the ion, which is -2 .