Question

Name the different methods of separation.

Answer 1

The various methods of separation are as follows.

1. Threshing: This process is used to separate grains or seeds from the stalk by beating the crops on hard surface or with the help of machines.
2. Winnowing: It is the process used to separate grains from chaff by blowing air through them or by allowing the wind to blow through them.
3. Hand-picking: When a small number of impure particles are present in a small quantity of a mixture, and the impure particles are distinguishable from the useful substance, they can be separated by hand-picking.
4. Sieving: Small substances pass through the pores of a sieve, but large impurities remain in the sieve. Thus, the difference in the sizes of the impurities and the useful material helps in this method of separation known as sieving.
5. Sedimentation and decantation: Separating insoluble solids suspended in a liquid by settling them is called sedimentation. After sedimentation is complete, the upper liquid, which is pure, is poured out without disturbing the sediment. This process is known as decantation.
6. Filtration: In this process, an insoluble solid and a liquid in a mixture can be separated by passing the mixture through a filtering device.
7. Evaporation and condensation: Heating a mixture of a liquid and a soluble solid changes the liquid into gas by evaporation, leaving behind the solid. The vapours of the liquid change back into the liquid state after coming in touch with a cold surface (by the process of condensation), thereby separating the soluble solid and the liquid in the original mixture.