Question

Find the number of electrons lost or gained in the following reaction
a) $Mn(OH{)}_2+H_2{O}_2\to Mn{O}_2+2H_{2}O$
b) $AlC{l}_3+3K\to Al+3KCl$ respectively.

• A. 2, 3
• B. 3, 2
• C. 4, 2
• D. 0, 0

Answer 1

The correct option is A 2, 3

a) $M{n}^{2+}\to M{n}^{4+}+2e^{-}$ (Oxidation)
$2e^{-}+H_2{O}_2\to 2H_{2}O$ (Reduction)
number of electron lost/gain = 2

b) $3K\to 3K^{+}+3e^{-}$ (Oxidation)
$3e^{-}+A{l}^{3+}\to Al$ (Reduction)
number of electron lost/gain = 3

Hence, the correct option is a