# What is the oxidation state of each element in Mn(NO_3)_2?

$\stackrel{+ I I}{M n}$, $\stackrel{+ V}{N}$, $\stackrel{- I I}{O}$,
The sum of the oxidation numbers is equal to the charge of the ion. Here, we have a neutral salt, and thus the sum of the oxidation numbers is $0$.
The salt derives from $M {n}^{2 +}$, and from 2 equiv $N {O}_{3}^{-}$. With respect to nitrate anion, the oxidation number of oxygen is generally $- I I$, and it is here. Nitrogen is fully oxidized in the $+ V$ state.