Which among the following purification methods is based on the principle of "Solubility" in two different solvents?

$A$ liquid with a high boiling point decomposes on simple distillation,but it can be steam distilled for its purification. Explain how this is possible.

Using the given figure,the ratio of $R_f$ values of sample $A$ and sample $C$ is $x \times 10^{-2}$. The value of $x$ is . . . . . . . .
Table: Paper chromatography of Samples
| Component | Distance from base line (cm) |
| :--- | :--- |
| Sample $A$ | $5.0$ |
| Sample $B$ | $6.5$ |
| Sample $C$ | $10.0$ |
| Solvent front | $12.5$ |

Ethylene has a high $b.p.$ and high vapour pressure at $100\,^{\circ}C$ and does not dissolve in water. Hence,ethylene is separated by this method:

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

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: