Olympiad Test: Sorting And Separation Of Materials -2 - Class 6 MCQ

• A: Stone is not transparent; it is opaque, meaning you cannot see through it. Glass is transparent, meaning you can see through it. So, this option is incorrect.
• B: A notebook does not have lustre (shiny surface) like a metal or polished object. An eraser also doesn’t have lustre. So, this option is incorrect.
• C: A piece of wood floats on water because wood is less dense than water, which means it does not sink. This is why this option is correct.
• D: Chalk does not dissolve in water; it breaks into pieces when put in water. So, this option is incorrect.

So, the correct answer is C.

• A: A pure substance is made up of only one type of particles, meaning it consists of only one kind of element or compound. For example, pure water (H₂O) or pure oxygen (O₂).
• B: A pure substance has a uniform texture throughout, meaning every part of it is the same.
• D: A pure substance has a fixed boiling point or melting point. For example, pure water always boils at 100°C at sea level and melts at 0°C.

Since all these points are true for a pure substance, the correct answer is C: All of them.

Salt is obtained from sea water through the process of evaporation. In this process, sea water is left in shallow ponds or pans, and the water evaporates due to heat from the sun, leaving behind the salt crystals.

• A: Centrifugation is used to separate substances of different densities (like separating cream from milk), but it's not used for salt extraction.
• B: Condensation is the process where a gas turns into a liquid, which doesn't apply to salt extraction.
• C: Sedimentation is the settling of solid particles from a liquid, but it's not how salt is obtained from sea water.

So, the correct answer is D: Evaporation.

Winnowing is a process used to separate lighter and heavier particles, typically used for separating grains from chaff. The heavier particles (like grains) fall straight down, while the lighter particles (like husk or chaff) are carried away by the wind. This separation happens because of the difference in their weight.

• A: Difference in colour is not the basis for winnowing.
• C: Difference in size might play a role in some separations, but winnowing is primarily based on weight.
• D: Difference in odours is not relevant to the process of winnowing.

So, the correct answer is B: Difference in their weight.

Sieving is the method used to separate a mixture of wheat and husk. Sieving works on the principle of size difference between the particles. In this case, wheat grains are larger, while husk particles are smaller, so when the mixture is passed through a sieve, the husk particles pass through the holes, while the wheat grains are left behind.

The brown-colored coating on the chopper and knife is rust. Rust forms when iron or steel reacts with moisture and oxygen in the air. This is called oxidation, and it results in a reddish-brown coating on the metal surface.

• A: Soil is not the brown coating that forms on metal tools.
• C: Iron is the metal, not the brown coating itself.
• D: While rust is made from iron, it is not correct to say that "both B and C" is the answer because rust specifically refers to the corrosion process, not iron itself.

So, the correct answer is B: Rust.

1. Sublimation: First, heat the mixture. Camphor sublimes, meaning it will change directly from a solid to a gas and can be separated from the mixture.
2. Adding water: After removing camphor, dissolve the salt in water, since salt is soluble in water, but sand is not.
3. Filtration: Use filtration to separate the sand from the saltwater solution. Sand will remain as the residue, while the salt will dissolve in the water.
4. Evaporation: Finally, evaporate the water from the salt solution to obtain the salt crystals.

So, the correct sequence is C: Sublimation, adding water, filtration, evaporation.

A saturated solution is a solution in which the maximum amount of a substance has already been dissolved at a given temperature. If you try to add more of that substance, it will not dissolve and will remain undissolved in the solution.

• B: A filtrate is the liquid that passes through a filter after filtration, which is not related to saturation.
• C: A solution is simply a mixture of two or more substances, but it doesn't necessarily mean it’s saturated.
• D: An unsaturated solution is one that can still dissolve more of the substance at a given temperature.

So, the correct answer is A: A saturated solution.

To separate paneer from curdled milk, filtration is typically used. After the milk curdles (usually with the addition of lemon juice or vinegar), the solid part (paneer) is separated from the liquid (whey) by passing the mixture through a filter cloth or a fine sieve.

• A: Condensation is the process of changing a gas to a liquid, not related to separating paneer.
• C: Evaporation is used for separating liquids by heating, but it's not used for separating paneer.
• D: Sedimentation involves solids settling at the bottom of a liquid, but it’s not the process for separating paneer.

So, the correct answer is B: Filtration.

Sand, chalk powder and sawdust are insoluble in water. They settle down in the test tubes. Sugar, salt and washing powder are soluble in water.