Question

Potassium manganate $\left( K _{2} MnO _{4}\right)$ is $\cdot$ obtained when
(1) formaldehyde reacts with potassium permanganate in presence of a strong alkali
(2) chlorine is passed into the solution of potassium permanganate
(3) $MnO _{2}$ is fused with $KOH$ in air
(4) $KMnO _{4}$ reacts with conc $H _{2} SO _{4}$

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (D)

$2 KOH + \underset{\text{manganese dioxide}}{MnO _{2}}+[ O ] \longrightarrow \underset{\text{potassium
manganate}}{K _{2} MnO _{4}}+ H _{2} O$
$ \underset{\text{tormaldehyde}}{HCHO} + \underset{\text{potassium
permanganate}}{2 KMnO _{4}}+ \underset{\text{alkali}}{2 KOH }\longrightarrow \underset{\text{potassium
manganate}}{2 K _{2} MnO _{4}}+ H _{2} O + HCOOH$