NCERT Solutions for Chapter 5 Separation of Substances Class 6 Science 

Short Notes for Class 6 Science Chapter 5 Separation of Substances

Handpicking, winnowing, sieving, sedimentation, decantation and filtration are some of the methods of separating substances from their mixtures. Husk and stones could be separated from grains by handpicking. Husk is separated from heavier seeds of grain by winnowing. Difference in the size of particles in a mixture is utilised to separate them by the process of sieving and filtration. In a mixture of sand and water, the heavier sand particles settle down at the bottom and the water can be separated by decantation. Filtration can be used to separate components of a mixture of an insoluble solid and a liquid. Evaporation is the process in which a liquid gets converted into its vapour. Evaporation can be used to separate a solid dissolved in a liquid. A saturated solution is one in which no more of that substance can be dissolved. More of a substance can be dissolved in a solution by heating it. Water dissolves different amount of soluble substances in it.
NCERT Solutions for Class 6th Science Chapter 5 Separation of Substances

Separation of Substances Questions and Answers

Chapter Name

Separation of Substances NCERT Solutions

Class

CBSE Class 6

Textbook Name

Science

Related Readings


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

Answer

Before using a substance, we need to separate harmful or non-useful substances that may be mixed with it. Sometimes, we separate even useful components if we need to use them separately.

For example:

  • We used to separate slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses by handpicking method.
  • Rice or pulses are usually washed before cooking. When we add water to these, the impurities like dust and soil particles get separated.

 

Question 2: What is winnowing? Where is it used?

Answer

Winnowing is the method of separating components of a mixture containing heavier and lighter components by wind or by blowing air. It is used to separate husk particles from seeds of grain.

 

Question 3: How will you separate husk or dirt particles from a given sample of pulses before Cooking?

Answer

Husk or bigger pieces of dirt particles can be removed from a sample of pulses by handpicking.

 

Question 4: What is sieving? Where is it used?

Answer

Sieving is the process of filtering components of a mixture of different sizes. Sieving allows fine particles to pass through the holes of the sieve, while the bigger impurities remain on the sieve.

Sieving is used in flour mills to separate broken particles of grains from flour. It is also used at construction sites to separate lumps, smaller stones from the mixture of sand and cement.


Question 5: How will you separate sand and water from their mixture?

Answer

To separate sand and water from their mixture, we follow the following steps:

  • Leave mixture to stand undisturbed for some time in a container.
  • Sand settles at the bottom of the container. It is called sedimentation.
  • Gently pour the water in another container (called decantation).
  • We may also use filter paper to remove fine particles of sand (called filtration)

 

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

Answer

Yes. Through sieving we can separate sugar mixed with wheat flour.

 

Question 7: How would you obtain clear water from a sample of muddy water?

Answer

Following steps are required to obtain clear water from muddy water:

  • Allow muddy water to stand undisturbed in a container.
  • After sometime, mud settles at the bottom of the container. This process is called sedimentation.
  • Upper layer is clear water.
  • Pour the clear water gently in another container. This process is called decantation.
  • To remove finer impurities we can filter this water again with the help of filter paper. This process is called filtration.

 

Question 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 churning.

(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.

 

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

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

(c) Separation of sugar from tea can be done with filtration. (False)

(d) Grain and husk can be separated with the process of decantation. (False)

 

Question 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 sugar before adding ice. Sugar dissolves in warm water more quickly than in cold water. We can dissolve more sugar before mixing ice in water.

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