Suggest separation technique(s) one would need to employ to separate the following mixtures.
1. Mercury and water
2. Potassium chloride and ammonium chloride
3. Common salt, water and sand
4. Kerosene oil, water and salt.
1. Separation can be done with a separating funnel. Mercury being heavy forms lower layer.
2. Sublimation can be used. Ammonium chloide sublimes.
3. Filtration followed by crystallisation techniques can be used here. Sand can be removed as an insoluble residue upon filtration. Upon evaporating the filtrate in a china dish to about one third followed by slow colling crystals of common salt $(\mathrm{NaCl})$ are formed.
4. Kerosene oil can be separated with a separating funnel. Water and salt can be separated either by distillation (water distils) or by evaporation (water evaporates). Salt is left behind as residue.