$A$ 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 one of the following mixtures can be separated by steam distillation technique?

Which two organic compounds are purified by the sublimation technique?

Fill in the blanks:
$1$. In formulas and reactions,the electron pair displacement is indicated by a curved arrow,and the single electron displacement is indicated by a ..........
$2$. There are more than .......... plates in the columns of fractional distillation.
$3$. Fractional distillation is used for the separation of liquids with a .......... difference in boiling points,and simple distillation is used for the separation of liquids with a .......... difference in boiling points.
$4$. The .......... technique is applied to separate different fractions of crude oil in petroleum.

Which one of the following techniques is not used to spot components of a mixture separated on a thin layer chromatographic plate?

When is distillation under reduced pressure used?