Methods of Separation: 17 MCQs with answers

C · Difference in weight

Winnowing uses wind to carry away the lighter chaff while the heavier grain falls almost vertically.

A · Threshing

Threshing is the process of beating harvested crops to separate grains from stalks.

C · Sand

Sand does not dissolve in water; it is an insoluble substance. Salt and sugar are soluble.

A · Solute

The substance that dissolves is the solute. Water is the solvent, and the mixture is the solution.

C · Dissolving

Dissolving is a process of mixing, not separating. Condensation, evaporation, and filtration are separation methods.

A · True

A combine harvester performs reaping, threshing, and cleaning of the crop in a single operation.

B · Saturated solution

A saturated solution is one in which no more solute can be dissolved at that temperature.

A · The quantity is small and stones look different

Hand-picking is preferred when the mixture is small, impurities are few, and they differ in size, shape, or colour.

D · It increases

Heating increases the solubility of a solute, so more sugar can dissolve in hot water than in cold.

D · Filtration

Sand is an insoluble solid, so filtration separates it from water; sand is retained on the filter paper.

D · Wind carries chaff away while grain falls almost vertically

The lighter chaff is carried by the wind, while the heavier grain falls almost vertically, forming a separate heap.

D · It retains insoluble solid particles and lets liquid pass

The filter paper has fine pores that trap insoluble solid particles while allowing the liquid to pass through.

A · Salt is dissolved and passes through the filter paper

Filtration only removes insoluble solids. Dissolved salt passes through the filter paper with the water.

C · Dissolve in water, filter, then evaporate

Salt dissolves in water while sand does not. Filtration removes sand, and evaporation recovers salt from the salt solution.

B · Stirring speeds up dissolving; heating increases solubility

Stirring changes the rate of dissolving, while heating changes the amount that can dissolve (solubility).

C · Powder has more surface area in contact with water

Powdered sugar has more surface area, so it dissolves faster. Solubility itself is not changed by powdering.

C · 1. Filtration to remove sand, 2. Dissolve salt in water, 3. Evaporation to recover salt

The correct sequence involves first using filtration to remove sand (which is insoluble), then dissolving the salt in water (since salt is soluble), and finally using evaporation to recover the salt from the salt solution. This method effectively utilizes the differing solubility properties of the components.