Question

$KMnO_{4}$ in basic medium is reduced to.

• A. $K_{2}MnO_{4}$
• B. $MnO_{2}$
• C. $Mn(OH)_{2}$
• D. $Mn^{2 +}$

Answer 1

Answer: (B)

$MnO_{2}$

Answer 2

$KMnO_{4}$ is first reduced to manganate and then to insoluble manganese dioxide. Colour changes first from purple to green and finally becomes colourless.

$2KMnO_{7} + 2KOH \rightarrow 2K_{2}MnO_{4} + H_{2}O + O$

$2K_{2}MnO_{4} + 2H_{2}O \rightarrow 2MnO_{2} + 4KOH + 2O$

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$2KMnO_{2} + H_{2}O\overset{\quad\text{alkaline}\quad}{\rightarrow}2MnO_{2} + 2KOH + 3\lbrack O\rbrack$