Question

What is the oxidation state of the phosphorus atom in phosphite, PO33-?

Answer 1

Phosphite ion is PO_{​​​​​3}​​​​^{​​​​3-}

It constitutes of phosphorus P and oxygen O and the overall charge or oxidation number of phosphite ion is -3

Oxidation number of O_{​​​​​​3} is 3*(-2) = -6. Oxygen exists in -2 oxidation state.

So, P + (-6) = -3

On solving P = +3

So, oxidation state of phosphorus in phosphite ion is +3