B. Answer Briefly
1. Why do we need to separate different components of a mixture?
2. When is handpicking used?
3. Which type of components of a mixture can be separated by sieving?
4. How will you remove impurities from pulses or rice grains before cooking?
5. How is winnowing useful to farmers?
6. How is common salt obtained from sea water?
7. Is it possible to separate a mixture of sugar and wheat flour? If so, how will you do it?
Answers
Answer:
1) We need to separate different components of a mixture to separate the useful components from the non-useful or some harmful components. ... So we need to separate different components of a mixture to separate the useful components from the nonuseful for some harmful components.
2)In this way salt get dissolved in water while sand we get as residue. Thus, we can say handpicking is used for separating slightly larger sized impurities such as pieces of dirt, stones, husk from wheat, rice, pulses etc. it can be used for those mixtures as well which differ in color shape or weight as well.
3)The process of separating solid constituents of different particle sizes; through a sieve is called sieving. Sieving is used while separating bran from flour. It is also used while separating pebbles from sand.
4)To separate husk or dirt particles from a given sample of pulses before cooking, we need to wash the pulses with water. Husk or dirt particles being lighter keep floating in water and pulses grain will settle down so we can easily remove them. Then, water with impurities can be removed by decantation.
5)Winnowing is an agricultural method developed by ancient cultures for separating grain from chaff. It can also be used to remove pests from stored grain. Winnowing usually follows threshing in grain preparation.
6)Common salt is obtained from sea-water by the process of evaporation. Sea water is trapped in large, shallow pools and allowed to stand there. The sun's heat evaporates the water slowly and common salt is left behind.