Multiple choice What is the oxidation number of manganese inmanganateion? +7 +6 +3 -681 Reveal answer Fill a bubble to check yourself B Correct answer Explanation The manganate ion is MnO4^2-. Oxygen has -2 oxidation state, so total from 4 oxygens = -8. For ion charge -2: x + (-8) = -2, therefore x = +6.