Suggest a suitable separation technique for the following:
$(i)$ Mercury and water.
$(ii)$ Coloured components from blue ink.
$(iii)$ Ammonium chloride and potassium chloride.
$(iv)$ Mixture of alcohol and water.

(N/A) $(i)$ Mercury and water: Since they are immiscible liquids with different densities,a separating funnel is used.
$(ii)$ Coloured components from blue ink: Chromatography is used as it separates components based on their different solubilities in a solvent.
$(iii)$ Ammonium chloride and potassium chloride: Sublimation is used because ammonium chloride sublimes upon heating,while potassium chloride does not.
$(iv)$ Mixture of alcohol and water: Fractional distillation is used because they are miscible liquids with different boiling points.