What is the oxidation number of phosphorus in P2O3?

O mostly always has a -2 charge, three O's = -6. The two P atoms must balance that charge with +6 since P2O3 overall has no charge. If 2 P = +6, then 1 P = +3.

is that right ?

2 answers

Yes, that's right. The oxidation number of P in P2O3 is +3.
thank you !!