what is the oxidation number of manganese in permanganate ion?

Answer 1

The permanganate ion is MnO₄^-

The oxidation number of Mn can be arrived at by considering the oxidation number of oxygen is -2 and the overall charge is -1. Thus, the oxygens provide -8 (-2 x 4) so the Mn must have an oxidation number = +7 in order to have an overall charge of 1-.