Give the difference between paper chromatography and thin layer chromatography.

What is the characteristic of $R_f$ value?

Describe the crystallisation technique used for the purification of organic compounds.

$A$ liquid contains a non-volatile impurity. Which technique will be applied for its purification?

Fill in the Blanks :
$(1)$ The steam distillation of $.......$ liquid is done and it is boiled at $.........$ temperature.
$(2)$ $.........$ and $........$ used to reduce pressure in distillation under reduced pressure.
$(3)$ In steam distillation the equation of total vapour pressure is $P = p_1 + p_2$ where $p_1$ is more than $...........$
$(4)$ $.........$ apparatus is used in differential extraction.

Which are the types of chromatography?