Calculate the oxidation number of phosphorus in the following species.
(a) `HPO_(3)^(2-)``" "`(b)`PO_(4)^(3-)`

Explanation

(a) Let the O.N of P in `HPO_(3)` be x `therefore` 1+x+3(-2)=-2 or x=+3
(b) Let the O.N of P in `PO_(4)^(3-)` be x `therefore` x+4(-2)=-3 or x=+5