* Oxygen's usual oxidation state: Oxygen almost always has an oxidation state of -2 in compounds.
* Neutral compound: CrO is a neutral compound, meaning the sum of the oxidation states must equal zero.
Let's represent the oxidation state of chromium as "x":
* x + (-2) = 0
* x = +2
Therefore, the oxidation state of chromium in CrO is +2.
