How do you solve this

Question

What is the oxidation state of nitrogen in nitrate (NO₃^- )

Answer 1

The oxidation state for oxygen (O) is 2- (except in peroxides).

Since NO3 has a net charge of 1-, we can now determine the oxidation state of nitrogen (N).

3 oxygens @ 2- each = -6

N must be 5+ in order for the polyatomic anion to have a net charge of 1-.