Glycerol is purified by

What is the difference between distillation,distillation under reduced pressure,and steam distillation?

State whether the following statements regarding steam distillation at reduced pressure are True or False:
$i$. It is used in the soap industry.
$ii$. Water pumps,vacuum pumps,or air pumps are used.
$iii$. Liquids with high boiling points do not decompose.
$iv$. The liquid is decomposed.
$v$. The liquid is boiled at a low temperature.

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

When the $TLC$ solvent reaches a height of $10 \, cm$,compound $(A)$ reaches $8 \, cm$ and compound $(B)$ reaches $6 \, cm$. Calculate the $R_f$ values of $(A)$ and $(B)$.

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.