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AIIMS 201827 May
Exam
AIIMS
Year
2018
Date
27 May
Subject
Chemistry
Chapter
d and f Block Elements

AIIMS 2018 · 27 May · Chemistry · d and f Block Elements

In acidic medium, which of the following becomes colourless?

In acidic medium, which of the following becomes colourless?

Options

  1. AMnO4−\mathrm{MnO}_4^{-}
  2. BMnO42−\mathrm{MnO}_4^{2-}
  3. CCrO42−\mathrm{CrO}_4^{2-}
  4. DFeO42−\mathrm{FeO}_4^{2-}

Correct answer

A. MnO4−\mathrm{MnO}_4^{-}

Step-by-step solution

MnO4−\mathrm{MnO}_4^{-}changes from purple to colourless in acidic solution while MnO42−\mathrm{MnO}_4^{2-} is stable in acidic medium. Yellow coloured CrO42−\mathrm{CrO}_4^{2-} changes to orange coloured Cr2O72−\mathrm{Cr}_2 \mathrm{O}_7^{2-} on acidifying and FeO42−\mathrm{FeO}_4^{2-} decomposes.
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