Which are the methods of purification of organic compounds?

What is the characteristic of $R_f$ value?

The distillation technique most suited for separating glycerol from spent-lye in the soap industry is:

Which one of the following can be purified by sublimation?

The method used for the separation of the mixture of products ($B$ and $C$) obtained in the following reaction is:

Fill in the blanks:
$1$. In differential extraction from two layers,the .......... layer is above because .............
$2$. The organic solvent used in differential extraction is .......... in water.
$3$. If an organic compound is ......... soluble in an organic solvent,then the continuous extraction technique is used.
$4$. ........ solution is added to produce the precipitate of halide for the estimation of halogen.