Question

When $Mn{O_2}$ is fused with $KOH$ and ${O_2}$, what is the product formed and its colour?
A. ${\text{MnO - Colourless}}$
B. $KMn{O_4}{\text{ - Purple}}$
C. ${{\text{K}}_2}{\text{Mn}}{{\text{O}}_4}{\text{ - Dark green}}$
D. ${\text{Mn}}{{\text{O}}_3}{\text{ - Black}}$

Answer 1

1. As the reaction is carried out in presence of atmospheric oxygen, and the atmospheric oxygen is green in colour.
2. ${H_2}O$is colourless in nature.
3. For balancing the reaction, use 2 moles of $Mn{O_2}$ and 4 moles of KOH and 1 mole of Oxygen.

Complete answer:
As per question we have to mix fused $Mn{O_2}$ with $KOH$ and ${O_2}$,
In that case,the reaction will be,
$2Mn{O_2} + 4KOH + {O_2} \to 2{K_2}Mn{O_4} + 2{H_2}O$
Here, It is clearly observed that when, $Mn{O_2}$ is fused with $KOH$ and ${O_2}$ we will get, $2{K_2}Mn{O_4}$ and ${H_2}O$
Here, we know that the oxidation state of Mn is +6.
The above reaction is placed in presence of atmospheric oxygen,
The colour of atmospheric oxygen is green.
Hence, the obtained product i.e. $2{K_2}Mn{O_4}$ will be green in nature.
We know that ${H_2}O$ is colourless in nature.
So, the final obtained product obtaining after the reaction when $Mn{O_2}$ is fused with $KOH$ and ${O_2}$ i.e. $2{K_2}Mn{O_4}$ and ${H_2}O$ will be green in colour.
Hence, right choice for this question will be ${{\text{K}}_2}{\text{Mn}}{{\text{O}}_4}{\text{ - Dark green}}$.

**Hence, Option C will be the correct choice for this answer.

Additional Information:**
1. Fused is a process when two or more elements are joined into a single element.
2. Colour of $Mn{O_2}$ is Brown/Black, and it is insoluble in water.
3. Colour of $KOH$ is milky white.
4. Colour of atmospheric oxygen is green/ dark-green.

Note:
1. As the obtained water after reaction is colourless in nature, so, the colour of final obtained element will be same as the colour of atmospheric oxygen ,
2. Balance the number of moles of $Mn{O_2}$,$KOH$ and ${O_2}$ for obtaining the balance equation.