Olympiad Test: Separation of Substances - Class 6 MCQ

X is winnowing, a process which uses the difference in weights of solids in a solid- solid mixture for separating the components.

Steel is uniform in its composition. Hence, it is a homogeneous mixture of solids.

Acetic acid and water are miscible liquids.

Liquification involves condensation of gases. The gas which condenses first gets separated. In all the other options, atleast one of the constituents is a solid.

It is a mixture of chalk powder, sugar and water. The chalk powder gets separated from sugar water by filtration. Later, sugar from sugar water is separated by distillation.

The correct answer is A: Sugar.

- The separation technique shown is crystallization, used to separate solids from a solution.
- Sugar can be separated from a sugar-water solution through crystallization.
- In this process, the sugar is dissolved in water, heated to dissolve more sugar, then cooled to allow sugar crystals to form and separate.
- Chalk powder, glass, and oxygen cannot be separated using crystallization.
R should be a substance which is soluble in water i.e., sugar.

Q should be a substance that is solid and insoluble in water i.e., chalk powder.

• Threshing: This is the primary method where stalks are beaten to release seeds. It can be done manually or with machines.
• Winnowing: After threshing, winnowing helps separate the chaff (outer husk) from the grains using wind or air.
• Sieving: This method can further clean the grains by filtering out smaller debris or broken seeds.
• All these methods are used in grain harvesting, but threshing is the main process for seed removal.

A compound is a pure substance containing only one kind of molecules.

Air is mixture of many gases and water vapours. The components of air are not chemically combined with one another.

A compound is a substance which contains only one type of molecules i.e. CO₂

An element is a substance which is made up of only one type of atoms. Oxygen (O₂) is diatomic in nature.

Minute solid particles float along with vapours (fumes) in the smoke. Hence, smoke is a solid-in-gas mixture.

Water is a pure substance and all others are solid-in-solid and solid-in-liquid mixtures.

A substance is pure if its composition is constant throughout and is made up of only one type of particles i.e. atoms or molecules

In a mixture, the constituent substances are mixed only physically but not combined chemically. A mixture is not a pure substance as its constituents retain their properties. So, a mixture can be either homogeneous or heterogeneous.

The components of a mixture are not chemically bound. Therefore, they retain their individual properties.

When a gas changes into a liquid, the process is known as condensation.

A mixture of solid-in-solid is called an alloy.

Aerated drinks are a mixture of carbon dioxide and water i.e. gas in liquid.