Question

Which of the following conversions can be carried out by both acidified $K_2Cr_2O_4$ and acidified $KMnO_4$?
(i) $Fe^{2+} \to Fe^{3+} + e^-$
(ii) $I^- \to$
(iii) $I^- \to I_2$
(iv) $H_2S \to S$

• A. (i) and (iii)
• B. (ii) and (iv)
• C. (i), (iii) and (iv)
• D. (i), (ii) and (iii)

Answer 1

Answer: (C)

$I ^{-}$is converted to $IO _3^{-}$by neutral or faintly alkaline $MnO _4^{-}$as shown below.
$2 MnO _4^{-}+ H _2 O + I ^{-} \longrightarrow 2 MnO _2+2 OH ^{-}+ IO _3^{-}$