Which property should a solvent used in crystallization possess?

Given below are two statements:
Statement $I$: Vapours of the liquid with higher boiling point condense before vapours of the liquid with lower boiling points in fractional distillation.
Statement $II$: The vapours rising up in the fractionating column become richer in high boiling component of the mixture.

State whether the following statements are True or False:
$(i)$ The purification of a solid is done by crystallisation.
$(ii)$ Crystallisation purifies the solid and distillation purifies the liquid.
$(iii)$ $A$ liquid is purified by sublimation.
$(iv)$ To separate a mixture of ammonium chloride and sodium chloride,the distillation method is applied.

On a thin layer chromatographic plate,an organic compound moved by $3.5 \ cm$,while the solvent moved by $5 \ cm$. The retardation factor of the organic compound is . . . . . . $\times 10^{-1}$.

Thin-layer chromatography is an example of

Two products $X$ and $Y$ are formed in the following reaction sequence: Benzene + $CH_3Cl \xrightarrow{Anhydr. AlCl_3} W \xrightarrow{dil. HNO_3/dil. H_2SO_4, warm} X + Y$. The suitable method that can be used for the separation of products $X$ and $Y$ is: