Question

Fusion of $Mn{O}_2$ with $KOH$ in presence of $O_2$ produces a salt W. An 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 an aqueous acidic solution, Y undergoes a disproportionation reaction to give Z and $Mn{O}_2$
• B. In both Y and $Z,\pi$ - bonding occurs between the p-orbitals of oxygen and the d-orbitals of manganese
• C. Y is diamagnetic in nature while Z is paramagnetic
• D. Both Y and Z are coloured and attain a tetrahedral shape

Answer 1

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

Both Y and Z are coloured and attain a tetrahedral shape

$Mn{O}_2\stackrel{KOH/O_2}{\to }\underset{W}{K_{2}Mn{O}_4}\underset{Oxidation}{\overset{Electrolytic}{\to }}\underset{X}{KMn{O}_4}$
Accordingly $Y=Mn{O}_4^{2-}$
$Z=Mn{O}_4^{-}$
a) $Mn{O}_4^{2-}\stackrel{acidicmedium}{\to }Mn{O}_2+Mn{O}_4^{-}$
b) In both $Mn{O}_4^{2-}$ and $Mn{O}_4^{-}$, $\pi$ - bonding occurs between the p-orbitals of oxygen and the d-orbitals of manganese.
c) In $Mn{O}_4^{2-}$ the oxidation state of $Mn$ is +6, so it possesses one valence electron and hence is paramagnetic in nature. While $Mn{O}_4^{-}$ is daimagnetic as it does not have any unpaired electron.
d) Both $Mn{O}_4^{2-}$ and $Mn{O}_4^{-}$ are coloured and attains tetrahedral shape.