Question

In preparing a chromatogram, the following precautions are taken. The solvent front must not be allowed to reach the top of the chromatography paper.
A) True.
B) False.

Answer 1

We all know that chromatography may be a technique which is employed to separate one compound from a mix which is dissolved during a fluid. During this technique the substances are separated depending upon their adsorption of compounds to the adsorbent if the compounds are skilled at the column at different rates which permit them to urge separated infractions. This system is often used on a little scale also as large scale to purify materials which will be utilized in future experiments. This method may be a sort of adsorption chromatography technique.

Complete step by step answer:
While performing chromatography, it's important to observe that the solvent should not reach the highest of the chromatography paper. This is due to that if the solvent reaches the highest of the paper, it won’t be possible to leave the space from the beginning to the front of the solvent and hence determine the $Rf$ value.
$\therefore$ the given statement is true.

Note:
Now we discuss about the principle of chromatography as,
If the mobile phase alongside the mixture which needs to be separated is passed from the highest of the column, the individual components of the mixture move at different rates. The components with lower adsorption and affinity to stationary phase travel faster in comparison to the components which have greater adsorption and affinity with the stationary phase. The components that move fast are removed first whereas the components that crawl are eluted out last. The adsorption of solute molecules to the column occurs during a reversible manner.