CBSE Questions for Class 6 Chemistry Separation Of Substances Quiz 1 - MCQExams.com

• 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.

Handpicking, winnowing, sieving, sedimentation, decantation and filtration are some of the methods of separating substances from their mixtures. 

When a saturated solution is heated, it becomes unsaturated, because it causes an increase in kinetic energy which leads to an increase in distance between the molecules of the liquid. So that the solute particles take free space present in the solvent. 

That is why saturated solution becomes unsaturated on heating.

Hence, option $$(B)$$ is the correct answer.

Wind winnowing is a method developed for separating grains from chaff. It is also used to remove weevils or other pests from stored grains. 

In its simplest form, it involves throwing the mixture into the air so that the wind blows away the lighter chaff, while the heavier grains fall back down for recovery. This includes techniques like using a winnowing fan (a shaped basket shaken to raise the chaff) or using a tool (a winnowing fork or shovel) on a pile of harvested grain.

Sugar syrup is a saturated solution of sugar.

From sugar syrup, solid sugar separates out as solid cooling and syrup become hard indicating that syrup is a saturated solution.

The method of separation of particles from a mixture based on the difference in size of particles is known as sieving. It uses sieve plates for separation of coarse particles from finer particles. Wheat flour is separated from wheat bran by the method of sieving.