Question

Reduction of oxidation state of central metal in aqueous permanganate ion involves
(1) 5 electrons in neutral medium
(2) 5 electrons in acidic medium
(3) 3 electrons in neutral medium
(4) 3 electrons in alkaline medium

• A. $1,2$
• B. $2,3$
• C. $1,3$
• D. $2,3,4$

Answer 1

Answer: (B)

In acidic medium
$MnO_{4}^{-}+8H^{+}+5e^{- 1} \rightarrow Mn^{2 +}+4H_{2}O$
In neutral medium
$MnO_{4}^{-}+2H_{2}O+3e^{-} \rightarrow MnO_{2}+4OH^{-}$
Hence, number of electrons gained in acidic and neutral mediums are 5 and 3 electrons respectively.