Which of the following is not an oxidation number of manganese?
+4
+7
+6
+5
+2

The oxidation number of a monatomic ion equals the charge of the ion. ... The alkaline earth metals (group II) are always assigned an oxidation number of +2. Oxygen almost always has an oxidation number of -2, except in peroxides (H2O2) where it is -1 and in compounds with fluorine (OF2) where it is +2

Explanation:

hope it helps

let that person have a turn to speak : )