Question

When is separation of substances necessary?Name four methods

used to separate solid substances.​

Answer 1

Answer:

The individual substances in a mixture can be separated using different methods, depending on the type of mixture. These methods include filtration, evaporation, distillation and chromatography.

If a substance does not dissolve in a solvent, we say that it is insoluble. For example, sand does not dissolve in water – it is insoluble.

Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered:

the sand stays behind in the filter paper (it becomes the residue)

the water passes through the filter paper (it becomes the filtrate)

Answer 2

Answer:

Separation is necessary when we want to remove unwanted things from a mixture. This also helps us to obtain the required substances.

Four methods to separate solid substances are : Threshing, Winnowing, Hand-picking and Sieving.