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

(N/A) Principle of crystallisation: The solubility of a component is less at low temperature than at high temperature,allowing pure crystals to be obtained from the solution. The impure component is dissolved in a suitable solvent,and impurities are removed by filtration. The solution is then heated,concentrated,and cooled,and the obtained crystals are separated out.
$(b)$ Distillation: Distillation is a technique used to purify liquids and separate liquid mixtures. Principle: Every liquid boils at a definite temperature,transitioning through $liquid$ $\rightarrow vapour$ $\rightarrow liquid$ states. In simple distillation,the impure liquid or liquid mixture is placed in a flask where the boiling point difference should be high (greater than $20^{\circ} C$). In the distillation flask,the more volatile liquid is condensed by a condenser and separated as a pure component. e.g.,Benzene - bromobenzene,chloroform - chlorobenzene,etc. mixtures are separated by this technique.
$(c)$ Chromatography: It is based on the principle of adsorption and partition. Each compound adsorbs and separates in a definite proportion. The stationary phase and mobile phase are used in the chromatography technique. In the adsorption process,the stable component (solid or liquid) is kept in the mobile liquid phase,where it is adsorbed and travels different distances. In partition chromatography,the stationary phase is a liquid or gas. The partition of components in the solvent differs,leading to their separation. Generally,chromatography is used to separate coloured compounds.