MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The oxidizing power of perhalate ions depends on their standard reduction potentials. A higher positive standard reduction potential indicates a stronger oxidizing agent. The standard reduction potentials (E^ ) for the reduction of perhalate ions to halate ions in acidic medium are: E^ ( BrO _4^- / BrO _3^-) = +1.74 V E^ ( IO _4^- / IO _3^-) = +1.65 V E^ ( ClO _4^- / ClO _3^-) = +1.20 V Since the reduction potential is highest for BrO _4^- and lowest for ClO _4^-, the decreasing order of oxidizing power is BrO _4^- > IO _4^- > ClO _4^-. The exceptionally high oxidizing power of BrO _4^- is due to the relative instability of the +7 oxidation state of bromine, which arises from the poor shielding of the 3d electrons (d-block contraction or middle row anomaly). Answer: BrO _4^- > IO _4^- > ClO _4^-