`KMnO_4` can be prepared from`K_2MnO_4` as per the reaction:
The reaction can go the completion by removing `OH^(ɵ)` ions by adding.

Options

A. `HCI`
B. `KOH`
C. `CO_2`
D. `SO_2`

Answer

C

Explanation

Since. `OH^(-)` are generated form work acid `(H_2O)`. And a weak acid (like `CO_2)`) should be used to remove it. Because if we add storng acid like (HCI) it reverse the reaction. KOH increses the concentration of `OH^(-)`, thus again shifts the reaction in backward side.
`CO_2` combines with `OH^(-)` to give carbonate which is easily removed. `SO_2` reacts with water to give strong acid. so it cannot be used.