'Adsorption' principle is used for which of the following purification method?

We need to identify which purification method uses the principle of adsorption.

Analysis of each method:

Extraction: This method is based on the principle of differential solubility of a compound in two immiscible solvents. It does not use adsorption.

Chromatography: This technique separates components of a mixture based on differential adsorption of the components on an adsorbent (stationary phase). The mixture is passed through a column of adsorbent (such as silica gel or alumina), and different components are adsorbed to different extents, allowing separation. Column chromatography, thin-layer chromatography (TLC), and other forms all rely on this principle.

Distillation: This method separates liquids based on differences in their boiling points. It does not involve adsorption.

Sublimation: This method separates substances based on their ability to sublime (convert directly from solid to vapor). It does not use adsorption.

The correct answer is Option (2): Chromatography.