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

The correct option is K₂MnO₄, MnO₂.

Step-by-step Explanation:

When solid potassium permanganate (KMnO₄) is heated strongly (to about 513 K or 240 °C), it undergoes thermal decomposition. The reaction breaks down the reactant into potassium manganate, manganese dioxide, and oxygen gas.

The balanced chemical equation for this thermal decomposition process is:

$2{\mathrm{KMnO}}_4\stackrel{\text{Δ}}{\to }{K}_2{\mathrm{MnO}}_4+{\mathrm{MnO}}_2+O_2$

In this reaction:
- K₂MnO₄ represents potassium manganate (a dark green solid).
- MnO₂ represents manganese dioxide (a black/brown solid).
- O₂ represents oxygen gas.

Therefore, the pair of substances formed by the decomposition of KMnO₄ among the options is K₂MnO₄ and MnO₂.