I'm pretty sure for FO2, the oxidation state of oxygen is +0.5, though I have no idea how it gains HALF an electron...
(There are also a few other compounds where oxidation number is sometimes not a whole number or when the oxidation number is not that valence charge, such as HClO <-- the oxidation no. of Cl is actually +1 and not -1. It's actually very unstable.)
As for the first compound, N could be +3. (Nitrogen can lose up to 5 electrons and gain up to 3 electrons.) Assuming F and Cl to have an oxidation no. of -1, O to have an oxidation of -2 and H to have an oxidation no. of +1. But then again, I could be wrong, because H could be -1 and so may differ for other elements. You may want to draw out and try to guess-and-check.
