Which of the following pair will be formed by the decomposition of KMnO₄?

The correct option is K₂MnO₄, MnO₂.

Step-by-step Explanation:

When potassium permanganate (${\mathrm{KMnO}}_4$) is heated, it undergoes thermal decomposition at around 513 K (240 °C).

The chemical reaction for this thermal decomposition process is represented by the following balanced equation:

$2{\mathrm{KMnO}}_4\to K_2{\mathrm{MnO}}_4+{\mathrm{MnO}}_2+O_2$

In this reaction:
1. ${\mathrm{KMnO}}_4$ is potassium permanganate (dark purple solid).
2. $K_2{\mathrm{MnO}}_4$ is potassium manganate (green solid).
3. ${\mathrm{MnO}}_2$ is manganese dioxide (black/brown solid).
4. $O_2$ is oxygen gas which is evolved.

Therefore, the pair formed by the decomposition of ${\mathrm{KMnO}}_4$ is $K_2{\mathrm{MnO}}_4$ and ${\mathrm{MnO}}_2$.