Question

$MnO_{2}$ when fused with $KOH$ and oxidised in air gives a dark green compound $X$. In acidic solution, $X$ undergoes disproportionation to give an intense purple compound $Y$ and $MnO_{2}$. The compounds $X$ and $Y,$ respectively, are

• A. $K_{2}MnO_{4} $ and $KMnO_{4}$
• B. $Mn_{2}$ and $KMnO_{4}$
• C. $K_{2}MnO_{4}$ and $Mn_{2}$
• D. $KMnO_{4} $and $K_{2}MnO_{4}$

Answer 1

Answer: (A)

$MnO_{2}$, when fused with $KOH$ and oxidised in air gives a dark green compound, $X,$ i.e. potassium manganate $(K_{2}MnO_{4})$. In acidic solution, $K_{2}MnO_{4}$ undergoes diproportionation to give an intense purple solution of potassium permanganate $Y$ and $MnO_{2}$.