By the crystallisation of an impure compound,if the mother liquor becomes coloured,what shall be done to remove the colour?

On heating,some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as

Which of the following statements is correct for paper chromatography?

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 $40 \% \ BaSO_4$.

Give a brief description of the principles of the following techniques taking an example in each case. $(a)$ Crystallisation $(b)$ Distillation $(c)$ Chromatography

Which of the following compounds is used as an adsorbent in column chromatography?