Each oxygen will have the oxidation number (2-), and we know the total charge is 1-. We have four oxygen atoms per molecule, so we can set up the equation: (charge on Mn) + 4(charge on O) = -1 (charge on Mn) + 4(-2) = -1 (charge on Mn) - 8 = -1 Charge on Mn = 7 The answer is C. 7
