Topics and Sub-Topics in Class 6 Science Chapter 3 Separation of Substances:
| Section Name | Topic Name |
| 3 | Separation of substances |
| 3.1 | Methods of separation |
Exercise Questions
Q 1. Why do we need to separate different components of a mixture? Give two examples.
Ans:
When two or more substances are mixed together, they form a mixture. Components of a mixture should be separated because some components may not be useful or may spoil the useful component of the mixture.
Examples:
Q 2. What is winnowing? Where is it used?
Ans:
Winnowing is a method used to separate grains from their outer coverings by tossing them into the air. The lighter outer coverings are blown away by the wind, while the heavier grains fall back down and are collected.
It's commonly used in agricultural practices, especially in rural areas, to separate grains like wheat, rice, or lentils from their outer coverings after threshing.
Q 3. How will you separate husk or dirt particles from a given sample of pulses before cooking?
Ans: Husk or dirt particles can be separated by winnowing, being lighter they will fly away from pulses.
Q 4. What is Sieving? Where can it be used?
Ans. Sieving is a method used to separate particles of different sizes by passing them through a sieve or a meshed screen. The smaller particles fall through the holes while the larger particles remain on top of the sieve.
It can be used in various scenarios:
Q 5: How will you separate sand and water from their mixture?
Ans:
Sand and water are separated from their mixture by the following steps:
a) The mixture is allowed to stand without any disturbances.
b) Now, sand settles down.
c) Slowly pour the water into another container to obtain sand in the bottom.
Q 6: Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Ans: Yes, it is possible to separate sugar mixed with wheat flour by using the following method:
Sieving:
Q 7: How would you obtain clear water from a sample of muddy water?
Ans:
We can obtain clear water from muddy water, by following these steps:
Q 8: Fill in the blanks:
(a) The method of separating the seeds of paddy from its stalks is called ___________.
(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 ___________.
(c) Salt is obtained from seawater by the process of ___________.
(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 ___________.
Ans:
(a) The method of separating the 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 decantation.
Q 9: True or false.
(a) A mixture of milk and water can be separated by filtration.
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing
(c) Separation of sugar from tea can be done with filtration.
(d) Grain and husk can be separated with the process of decantation.
Ans:
a) False
b) False
c) False
d) False
Q 10: 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?
Ans: Add ice to the lemonade after dissolving the sugar. It's possible to dissolve more sugar when it's dissolved in water at a higher temperature before adding ice.