Which of the following pairs of organic compounds can be purified by the sublimation technique?

What is mother liquor?

Glycerol is purified by

How do you perform the purification of the following?
$(i)$ The boiling point of liquid $X$ is $450 \ K$ and it decomposes at $400 \ K$ temperature.
$(ii)$ Mixture of $60 \% \ \text{Camphor}$ and $40 \% \ BaSO_4$.

Which one of the following methods is suitable to separate a mixture of $n$-pentane and toluene?

The species that exhibits the highest $R_f$ value in a thin layer chromatogram using a non-polar solvent on a silica gel plate is