Suggest separation technique$(s)$ one would need to employ to separate the following mixtures:
$(a)$ Mercury and water
$(b)$ Potassium chloride and ammonium chloride
$(c)$ Common salt,water and sand
$(d)$ Kerosene oil,water and salt

(N/A) Separation by using a separating funnel,as they are immiscible liquids with different densities.
$(b)$ Sublimation,as ammonium chloride sublimes upon heating while potassium chloride does not.
$(c)$ Filtration to remove sand,followed by evaporation to separate common salt from water.
$(d)$ Separation by using a separating funnel to remove kerosene oil,followed by evaporation or distillation to separate salt from water.