Question

Th science project on separation of substances

Answer 1

Answer:

Explanation:

Separating solid from a mixture of solids

Handpicking: It is the simplest method of separation of substances. This method is used only when unwanted material is in small quantity.

Threshing: Threshing is used for separating seeds from the harvested stalks.

Sieving: When the size of particle it too small to be picked by hand or when the quantity is too large, sieving is used for separating substances. A sieve; having holes of proper size is used. The bigger particles are retained by the sieve whereas the smaller ones pass through it. For example; this method is used for separating bran from flour, sand from gravel, pearls of different sizes, etc.

Winnowing:The process of separation of lighter particles from heavier particles; with the help of wind; is called winnowing. This method is used for separating grains from husk. Farmers drop the mixture of wheat and husk from a height. The husk is carried by the wind and form a heap at a small distance away. The wheat grains being heavier fall vertically to form a separate heap.

Combine Harvester: Modern farming involves use of a machine; called combine harvester. This machine harvests, threshes and winnows in a single operation.