When determining oxidation numbers, how can you find the oxidation number of a monatomic ion (an ion made of a single element)?

• A. It is equal to the number of valence electrons the atom has in its neutral state.
• B. It is always $0$ because the particle is an ion.
• C. It is equal to the ion’s charge (for example, in $N^3$, the oxidation number of $N$ is $\mathrm{-}3$).
• D. It is found by assigning $\mathrm{-}2$ to oxygen and $\mathrm{+}1$ to hydrogen, then balancing.

Answer: (C)