Question

To separate a mixture in which the solid is insoluble in the liquid, such that the solid is heavier than the liquid, which of the following methods of separation are most suited?

• A. Sedimentation and decantation
• B. Evaporation followed by condensation
• C. Filtration
• D. Condensation and crystallization

Answer 1

Answer: (A)

Sedimentation and decantation

• To separate solids that are insoluble in liquids and the solid is heavier than the liquid, sedimentation and decantation method is most suited. By leaving the mixture undisturbed for a long time, the larger and heavier solid particles settle down leaving the clear liquid above it. Once the solid has completely settled down, the clear liquid above is poured out leaving behind the insoluble heavy solid particles (decantation).
• Evaporation cannot be suggested as a method of separation here because it is not mentioned whether the liquid or the solid is volatile or not.
• Filtration is not necessary as the solid particles are heavier and will automatically settle. If the solid particles were not heavy and will not settle down easily, we could have opted for filtration method.
• Condensation and crystallisation method is also not suited because we do not know from the question whether the solid is crystallisable or not.