Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Thin layer chromatography is an adsorption chromatography.
Reason R: A thin layer of silica gel is spread over a glass plate of suitable size in thin layer chromatography which acts as an adsorbent.
In the light of the above statements, choose the correct answer from the options given below

We are given an assertion-reason question about Thin Layer Chromatography (TLC).

Assertion A: Thin layer chromatography is an adsorption chromatography.

This is true. In TLC, the separation of components occurs based on the principle of adsorption. The components of the mixture are adsorbed to different extents on the stationary phase (the thin layer of adsorbent), and they move at different rates when a solvent (mobile phase) moves up the plate by capillary action.

Reason R: A thin layer of silica gel is spread over a glass plate of suitable size in TLC which acts as an adsorbent.

This is also true. In TLC, a thin layer (about 0.2 mm thick) of an adsorbent such as silica gel ($$SiO_2 \cdot xH_2O$$) or alumina ($$Al_2O_3$$) is coated uniformly on a glass plate. This layer acts as the stationary phase and serves as the adsorbent.

Now, the reason directly explains why TLC is classified as adsorption chromatography — it is because the stationary phase (silica gel layer) functions as an adsorbent, and separation occurs through differential adsorption of components on this layer. So R is the correct explanation of A.

Hence, the correct answer is Option A.