Question

Fusion of $Mn{O}_2$ with $KOH$ in presence of $O_2$ produces a salt $W$. Alkaline solution of $W$ upon electrolytic oxidation yields another salt $X$. The manganese containing ions present in $W$ and $X$, respectively, are $Y$ and $Z$. Correct statement(s) is(are)

• A. In aqueous acidic solution, $Y$ undergoes disproportionation reaction to give $Z$ and $Mn{O}_2$
• B. Both $Y$ and $Z$ are coloured and have tetrahedral shape
• C. $Y$ is diamagnetic in nature while $Z$ is paramagnetic
• D. In both $Y$ and $Z$, $\pi$-bonding occurs between $p$-orbitals of oxygen and $d$-orbitals of manganese

Answer 1

Answer: (A), (B), (D)

$2Mn{O}_2+4KOH+O_2\stackrel{\text{Fusion}}{\to }\underset{\text{(W)}}{2K_{2}Mn{O}_4+2H_{2}O}$
Electrolysis of aq $K_{2}Mn{O}_4$ oxidises $Mn{O}_4^{2-}$ to $Mn{O}_4^{-}$
$\underset{\text{(W)}}{K_{2}Mn{O}_4}+2H_{2}O\stackrel{\text{Electrolysis}}{\to }\underset{\text{(X)}}{2K_{2}Mn{O}_4+2KOH+H_2}$
$K_{2}Mn{O}_4$ in acidic medium undergoes disproportionation
$\underset{\text{(Y)}}{3Mn{O}_4^{2-}}+4H^{+}\to \underset{\text{(Z)}}{2Mn{O}_4^{-}+Mn{O}_2+2H_{2}O}$
$K_{2}Mn{O}_4$ is green in colour and $KMn{O}_4$ is in purple colour. Both are tetrahedral in shape involving p$\pi$ - d$\pi$ bond.