Oxygen is mostly negative besides linking with F (fluor).
Oxygen is mostly in -2 oxidation states besides peroxide, superoxides.
Alkaline and alkaline-earth metals are respectively in +1 and +2 ox. states.
Normal molecule must be in 0 ox. state
K Mn O4 - oxidation state of Mn is “x”. So,
(+1) + (x) + (2*(-4)) = 0
x = 7
