Which one of the following options represents the decreasing order of oxidation number of the central atom in: Cr ₂ O ₇²⁻, CrO ₂⁻, MnO ₄⁻, BrO ₃⁻

Step-by-step solution

For Cr ₂ O ₇²⁻ : Let the oxidation number of Cr be x . Then 2x + 7(-2) = -2 , which gives 2x = 12 , so x = +6 . For CrO ₂⁻ : Let the oxidation number of Cr be x . Then x + 2(-2) = -1 , which gives x - 4 = -1 , so x = +3 . For MnO ₄⁻ : Let the oxidation number of Mn be x . Then x + 4(-2) = -1 , which gives x - 8 = -1 , so x = +7 . For BrO ₃⁻ : Let the oxidation number of Br be x . Then x + 3(-2) = -1 , which gives x - 6 = -1 , so x = +5 . Comparing the oxidation numbers: MnO ₄⁻ (+7) > Cr ₂ O ₇²⁻ (+6) > BrO ₃⁻ (+5) >