In chromatography,what does $R_f$ stand for?

Write the applications of chromatography.

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.

$A$ liquid with a high boiling point decomposes on simple distillation,but it can be steam distilled for its purification. Explain how this is possible.

$A$ chromatography column,packed with silica gel as the stationary phase,was used to separate a mixture of compounds consisting of $(A)$ benzanilide,$(B)$ aniline,and $(C)$ acetophenone. When the column is eluted with a mixture of solvents,hexane: ethyl acetate $(20: 80)$,the sequence of obtained compounds is:

Which technique is used for the separation of a compound present in an aqueous solution?