Answer:-

The oxidation state of manganese (Mn) in chemical compounds can be determined by considering the overall charge of the compound and the known oxidation states of the other elements involved.

(i) In MnO4^2-, you have a 2- charge for the entire ion. Oxygen typically has an oxidation state of -2, so you have 4 oxygen atoms contributing a total charge of -8. To balance the charge, manganese (Mn) must have an oxidation state of +6. So, in MnO4^2-, manganese is in the +6 oxidation state.

(ii) In MnO4^-, you have a 1- charge for the entire ion. Using the same reasoning as above, oxygen contributes -2 each, so the total contribution from oxygen is -8. In this case, manganese (Mn) must have an oxidation state of +7 to balance the charge. So, in MnO4^-, manganese is in the +7 oxidation state.