The organic compound which can be purified by steam distillation is

$A$ mixture of three compounds $A, B, C$ is passed through a column of $Al_2O_3$ by using alcohol as eluant. The order in which they are eluted out of the column is $C, B, A$. Which of the following statements is true?

Which of the following methods is used for the purification of organic compounds?

Which of the following statements about $TLC$ are correct?
$(i)$ Glycine is identified on $TLC$ plate due to its colour.
$(ii)$ Amino acids can be detected by spraying the $TLC$ plate with $Ninhydrin$ solution.
$(iii)$ The retardation factor $(R_f)$ is the ratio of the distance travelled by the solute to that of the solvent from the base line.
$(iv)$ Sodium chloride is commonly used as an adsorbent.

Glycerol boils at $290\,^oC$ with slight decomposition. Impure glycerin can be purified by:

What is $R_f$?