Class 6 Science Chapter 5 Important Questions

Class 6 Science Chapter 5 Important Questions of Separation of Substances. These extra questions answers help the student to revise the complete chapter in easier way. Class 6 Science Chapter 5 Extra Question Answers ensure to score good marks.

All the important questions from the intext part as well as exercises part are included here to provide a complete revision.

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Class 6 Science Chapter 5 Important Questions for 2020-2021

Class: 6Science
Chapter: 5Separation of Substances
Contents:Important Extra Questions

Class 6 Science Chapter 5 Important Extra Questions Set – 1

Why do we separate substances? Give examples.

We need to separate harmful or non-useful substances that may be mixed with the substance used. Sometimes, we separate even useful components if we need to use them separately.
For example: Tea leaves are separated from the liquid with a strainer, while preparing tea. Grain is separated from stalks, while harvesting. Milk or curd is churned to separate the butter.

What do you mean by “homogeneous and heterogeneous mixture”?

A mixture in which all of its components are evenly distributed throughout the mixture is known as homogeneous mixture e.g. mixture of salt and water.
A mixture in which its components are not distributed evenly throughout the mixture is known as heterogeneous mixture. e.g. mixture of oil and water.

What happens when sand and powdered leaves fall at the same place?

When sand and powdered leaves are at the same place, and sand reaches that place vertically and leave are blown away, because sand is heavier than powder leaves. This process is called winnowing.

What do you mean by hand picking? Explain with example.

Handpicking can be used for separating slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses. The quantity of such impurities is usually not very large. In such situations, we find that handpicking is a convenient method of separating substances.
As an example: Spread the grain on a sheet of paper. There are many pieces of stone, husks, broken grain and particles of any other grain in it. Now, remove with your hand the pieces of stone, husks and other grains from it. This method is called “handpicking”.

What is “Threshing”?

When bundles of wheat or paddy stalks are beaten to free the grain seeds. This process is called “threshing”.

What is Sieving?

Sieving is a process which allows fine particles to pass through the holes of sieve, while the bigger impurities remain on the sieve.
It is used in flour mill in which impurities like husk and stones are removed from wheat. Sieves being used at construction sites to separate pebbles and stones from sand.




Class 6 Science Chapter 5 Important Extra Questions Set – 2

How does one separate grain seeds from there stalks? Explain.

The process used for separating grain seeds from their stalks is called threshing. It can be done by –
i) Manually beating the dry stalks on the ground or a hard surface to shake off the dried grains.
ii)Trampling them under the feet of animals like bullocks.
iii)Using threshing machines.

In which condition winnowing process is used?

When we get a mixture of dry sand with sawdust or powdered dry leaves. And keep this mixture on a plate or a newspaper. Look at this mixture carefully.
There are lots of question can arise. Can the two different components be made out easily? Would it be possible to separate the components by handpicking?
In that condition, when the sizes of particles of the two components are similar. Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air.
This method is commonly used by farmers to separate lighter husk particles from heavier seeds of grain.

What do you mean by winnowing process?

The method of separating heavier with lighter components of a mixture by wind or by blowing air, is called winnowing.

Which method of separating tea leaves from prepared tea is better, decantation or filtration?

Filtration is better method than decantation to separate tea leaves from prepared tea.

Class 6 Science Chapter 5 Important Extra Questions Set – 3

The best way to carry out the filtration of the mixture of water and sand is to use filter paper not cloth. Why?

The best way to carry out the filtration of the mixture of water and sand is to use filter paper not cloth because filter paper has fine pore while cloth has larger holes than filter paper. The particles of sand do not pass through filter paper but these may pass from cloth to filtrate.

How are dust or soil particles (impurities) separated from rice or pulses before cooking?

Rice or pulses are usually washed before cooking. When we add water to these, the impurities like dust and soil particles get separated. These impurities go into water, which becomes a little muddy. And the heavier component in a mixture settles after water is added to it, the process is called sedimentation.

What is decantation?

Decantation is a method of separation used after sedimentation in which when insoluble particles settle down, the clear liquid is poured into another container.

What do you mean by filtration?

The process of separating insoluble components from a mixture using a filter paper or cloth is called filtration.

What is Sedimentation?

When the mixture is allowed to stand for some time, the heavier components in the mixture settled at the bottom and the process is called sedimentation.
For example, when mixture of sand and water is allowed to stand for some time, the particles of sand settle down at the bottom of the vessel. The settling down of sand particles is called sedimentation.




Class 6 Science Chapter 5 Important Extra Questions Set – 4

What do you mean by “Supernatant”?

The clear liquids that remains above the sediments is called supernatant.

What do you mean by “Loading”?

The process of adding of alum in muddy water which loads the mud particles and speeds up sedimentation, is known as loading.

What do you mean by condensation? Give Example.

The process of conversion of water vapor into its liquid form is called condensation. Take a metal plate with some ice on it. Hold the plate just above the spout of the kettle. When the steam comes in contact with the metal plate cooled with ice, it condenses and forms liquid water. The water drops that you observed falling from the plate, were due to condensation of steam.

How is common salt obtained from seawater?

Sea water is allowed to stand in shallow pits. Due to solar heat, water in the pits get evaporated. After some days, the water evaporates completely and the solid salts remain in the pits. These salts are further purified to get pure common salt.

Class 6 Science Chapter 5 Important Extra Questions Set – 5

If you are given two transparent clear liquids, without tasting, how would you determine which is distilled water and which is a solution of salt water?

We will differentiate between the distilled water and the solution of salt water without tasting by the process of evaporation. On evaporation, the salt water container will leave a caky residue which is absent from the distilled water.

How will you separate sand and water from their mixture?

To separate sand and water from their mixture we follow the following steps:
i)Leave mixture to stand undisturbed for some time in a container.
ii)Sand settles at the bottom of the container it is called sedimentation.
iii)Gently pour the water in another container (called decantation).
iv)We may also use filter paper to remove fine particles of sand (called filtration).

What do you mean by solution and solubility?

A solute is the substance that is dissolved in the solvent to form the “solution”.
The ability of a substance to dissolve in water to form a solution is known as “solubility”.

What will happen if a large quantity of a substance is forced to dissolve in a fixed amount of water?

If a large quantity of a substance is forced to dissolve in the fixed amount of water then after a certain quantity of the substances has been dissolved, it will not dissolve due to saturation.

A mixture of iron nails, salt, oil and water is provided to you. Give stepwise method to separate each component from this mixture?

Steps for the separation of iron nails, salt, oil and water.
Iron nails are separated from the mixture by using magnets. Then by using decantation oil and water is separated. Oil being lighter forms the upper layer in the beaker and we can decant off the upper layer of oil.
Now, the mixture contains dissolved salt and water. Salt can be obtained from the water by the process of evaporation. The water present in salt solution will form water vapor and then the salt is left behind.



Separation of a mixture of Sawdust and Sugar

Following steps are used to separate a mixture of sawdust and sugar:

    1. Add water to the mixture.
    2. Sugar present in the mixture dissolves in water but sawdust does not.
    3. The solution is then filtered through filter paper.
    4. We will get sugar solution as filtrate and sawdust will remain on the filter paper.
    5. Then the solution is heated and when water evaporates completely, sugar is left behind.