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Question: The substance used as an adsorbent in the column chromatography is: A. \[{\text{N}}{{\text{a}}_2}{...

The substance used as an adsorbent in the column chromatography is:
A. Na2O{\text{N}}{{\text{a}}_2}{\text{O}}
B. Na2SO4{\text{N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}
C. Al2O3{\text{A}}{{\text{l}}_2}{{\text{O}}_3}
D. alum

Explanation

Solution

Chromatography is a separation technique in which a mobile phase carrying a mixture is caused to move in contact with a selectively absorbent stationary phase. There are different kinds of chromatography, which differ in the mobile and the stationary phase used. Column chromatography is used for the separation and purification of both solids and liquids.

Complete step by step solution:
Column chromatography is a solid-liquid technique in which the stationary phase is a solid and mobile phase is a liquid. The principle of this technique is adsorption. The components move depending on their relative affinities. The components of mixture are separated by using a glass column packed with stationary phase and the liquid mobile phase flowing continuously through the column.
The solvent used as a mobile phase is called eluent. Compounds attracted more strongly by the mobile phase will move rapidly through the column and elute from the column dissolved in the eluent. The compound more strongly attracted to the stationary phase will move slowly through the column.
The usual adsorbents employed in column chromatography are silica, alumina, calcium carbonate, calcium phosphate, magnesia, starch etc. Alumina is generally suitable for chromatography of less polar compounds. Silica gel gives good results with compounds containing polar functional groups.

So the correct answer is option C

Note: Adsorption chromatography is a surface phenomenon. The stationary phase is solid and the mobile phase is liquid or gas. The adsorbents are porous and have high surface area. Adsorbents require activation before use. This can be achieved by heating, where adsorbent loses water and other adsorbed materials. There is an optimum temperature for activation. The optimum temperature for alumina is 400∘C{\text{40}}{{\text{0}}^ \circ }{\text{C}}.