CBSE Class 6 Science Separation of Substances VBQs

Fill up the blanks-

(a) The method of separating seeds of paddy from its stalks is called threshing.

(b) When milk cooled after boiling is poured onto a piece of cloth, the cream (malai) is left behind on it.

This process of separating cream from milk is an example of filtration.

(c) Salt is obtained from seawater by the process of evaporation.

(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called Sedimentation and decantation.

True or false?

Question. Separation of sugar from tea leaves can be done with filtration. (True)
Answer : True

Question. A mixture of milk and water can be separated by filtration. (False)
Answer : False

Question. Grain and husk can be separated with the process of decantation. (False)
Answer : False

Question. A mixture of powdered salt and sugar can be separated by the process of winnowing. (False)
Answer : False

Short Answer Type Questions.

Question. What is sieving? Where is it used?
Answer : Sieving is a method of separation which allows the fine flour particles to pass through the holes of the sieve while the bigger impurities remain on the sieve. It is used at home to separate pebbles and stones from sand.

Question. What is winnowing? Where is it used?
Answer : Method of separating the components from a mixture is known as winnowing. In this method heavier and lighter components of a mixture are separated by wind or by blowing air. This method is used to separate grains from husk.

Question. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?
Answer : We should add ice after dissolving sugar because the dissolving power of water decreases with decrease in temperature. So, if we add ice before dissolving sugar, less amount of sugar will get dissolved.

Question. How will you separate sand and water from their mixture?
Answer : By Sedimentation and decantation: The mixture is allowed to stand without any disturbances, and sand settles down. Now slowly pour the water into another container to obtain sand in the bottom. We can also use filtration.

Question. How will you separate husk or dirt particles from a given sample of pulses before cooking?
Answer : Husk and dirt particles are separated from pulses by hand picking.

Question. How would you obtain clear water from a sample of muddy water?
Answer : By Sedimentation and decantation: Allow muddy water to stand. Mud gets settled down in the water. Slowly pour water to another container. We can also obtain pure water from muddy water by filtration.

Question. Why do we need to separate different components of a mixture? Give two examples.
Answer : We need to separate different components of a mixture:
(i) To separate harmful or non-useful substances that may be mixed with it.
(ii) To separate even useful components if we need to use them separately.
Examples: (i) Milk or curd is churned to separate the butter.
(ii) Grain is separated from stalks, while harvesting

Question. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer : Yes. Mix sugar and wheat flour in water. Stir the solution to allow sugar to dissolve. Now filter the mixture. Filtrate contains sugar solution and residue will be wheat flour.