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

What criterion is followed for the selection of the stationary phase in chromatography?

The most suitable method of separation of a $1:1$ mixture of $ortho$- and $para$-nitrophenols is:

$A$ mixture of dichloromethane and aniline can be separated by

Which technique among the following is most appropriate for the separation of a mixture of $100 \ mg$ of $p-$nitrophenol and picric acid?

State whether the following statements regarding fractional distillation are True or False:
$(i)$ The freezing of vapour of a liquid with a high boiling point takes place first.
$(ii)$ In the column,the more volatile liquid is present in a higher concentration in the vapour phase at higher levels.
$(iii)$ The condensed liquid flows down and provides heat to the vaporizing liquid.
$(iv)$ The liquid with the highest boiling point reaches the top of the column.