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JEE Main 202621 JanuaryMorning Shift
Exam
JEE Main
Year
2026
Date
21 January
Shift
Morning Shift
Subject
Chemistry
Chapter
d and f Block Elements

JEE Main 2026 · 21 January · Morning Shift · Chemistry · d and f Block Elements

MnO_ 4 ^ 2- , in acidic medium, disproportionates to :

MnO42−\mathrm{MnO}_{4}{ }^{2-}, in acidic medium, disproportionates to :

Options

  1. AMnO4−\mathrm{MnO}_{4}{ }^{-}and MnO2\mathrm{MnO}_{2}
  2. BMn2O7\mathrm{Mn}_{2} \mathrm{O}_{7} and MnO2\mathrm{MnO}_{2}
  3. CMn2O7\mathrm{Mn}_{2} \mathrm{O}_{7} and MnO
  4. DMnO4−\mathrm{MnO}_{4}{ }^{-} and MnO

Correct answer

A. MnO4−\mathrm{MnO}_{4}{ }^{-}and MnO2\mathrm{MnO}_{2}

Step-by-step solution

MnO42−MnO_4^{2-} (manganate) has Mn in +6 oxidation state.
In acidic medium, it undergoes disproportionation where Mn is simultaneously oxidized and reduced:
Oxidation: +6→+7+6 \rightarrow +7 (forms MnO4−MnO_4^-, permanganate)
Reduction: +6→+4+6 \rightarrow +4 (forms MnO2MnO_2)
Reaction: 3MnO42−+4H+→2MnO4−+MnO2+2H2O3MnO_4^{2-} + 4H^+ \rightarrow 2MnO_4^- + MnO_2 + 2H_2O
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