Question

What happen when crystals of potassium permanganate are put at the bottom of glass filled with water

Answer 1

It will start dissolving (by simple diffusion).

Answer 2

Answer: Diffusion of potassium permanganate in water occurs.

Explanation: Potassium permanganate crystals are purple - brown in color.

When the crystals of potassium permanganate are put in a glass filled with water, the color of the crystals of $KMnO_4$ crystals gets spread in the whole water solution.

Diffusion is a process of spreading of solute in the solvent very widely.

Hence, the spreading of color of $KMnO_4$ in water is a diffusion process.