NCERT Solutions for Class 6 Science Chapter 5 Separation Of Substances

Q.1 Why do we need to separate different components of a mixture? Give two examples.

Answer :

When two or more substance mix together we call it a mixture. Some time different component of mixture are not useful or may even harmful so we need to separate different components of a mixture.
Example: (a) Stone pieces from wheat, rice or pulses are picked out by hand.
(b) sand mixed in water are separated by sedimentation.

Q.2 What is winnowing? Where is it used?

Answer :

Winnowing is used to separate heavier and lighter components of mixture by wind or by blowing air. This method is used to separate grains from husk.

Q.3 How will you separate husk or dirt particles from a given sample of pulses before cooking?

Answer :

Separate husk or dust particles from pulses before cooking by hand picking or winnowing.

Q.4 What is sieving? Where is it used?

Answer :

sieving is a process in which fine particles are sieved through holes of the sieve while the bigger impurities remain on the sieve.
It is used to move husk from wheat

Q.5 How will you separate sand and water from their mixture?

Answer :

we will separate sand and water from their mixture by the process of sedimentation.

Q.6 Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

Answer :

Yes it is possible to separate sugar mixed with wheat flour by sieving method.

Q.7 How would you obtain clear water from a sample of muddy water?

Answer :

We obtain clear water from a sample of muddy water by sedimentation or decantation method.
i) Allow muddy water to stand
ii) Mud gets settled down in the water
ii) Slowly pour water to another container

Q.8 Fill up the blanks.
(a) The method of separating 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 ___________.

Answer :

(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 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.

Answer :

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?

Answer :

We should add ice after dissolving the sugar. it will be possible to add more sugar before adding ice.