When is steam distillation applied?

$X$ and $Y$ have $R_f$ values of $0.75$ and $0.25$ respectively. In column chromatography,which component is obtained first?

State True or False for the following statements regarding steam distillation:
$(i)$ The liquid is boiled at a temperature lower than its normal boiling point.
$(ii)$ The vapour pressure of the liquid is less than the atmospheric pressure.
$(iii)$ The sum of the vapour pressure of the liquid and the vapour pressure of water is equal to the atmospheric pressure.
$(iv)$ The mixture of organic liquid and water is obtained as the distillate.
$(v)$ The condensation of the mixture of water vapour and organic liquid vapour takes place.

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 methods is used for the purification of organic compounds?

Explain differential extraction.