a) i. Mn³⁺ is a good oxidizing agent because the +2 oxidation state of Mn is more stable than +3. Mn³⁺ is reduced to Mn²⁺.
ii. Because values of ionization energy first and second are not regular for first row transition metals of 3d series.
iii. Oxygen can form multiple bonds while fluorine can form single bonds.
b) i) 2CrO₄²⁻ + 2H⁺ → Cr₂O₇²⁻ + H₂O
ii) 2KMnO₄ → K₂MnO₄ + MnO₂ + O₂