CBSE Class 6 Science Chapter 5 Separation of Substances NCERT Solutions

CBSE Class 6 Science 

Chapter 5: Separation of Substances

NCERT Solutions

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

Answer: We separate different components of a mixture, to remove the harmful and non-useful substances. It is also done to separate two useful components in a mixture. For Example, Stones are from rice or wheat is separated out from it by the method of handpicking. In construction sites, pebbles and stones are removed from sand by sieving.

2. What is winnowing? Where is it used?

Answer: Winnowing is the method of separating components by wind or by blowing air. It is commonly used by farmers to separate lighter husk particles from heavier seeds of grain.

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

Answer: We can separate the husk or dirt particles from pulses by the method of handpicking. If the husk and dirt particles are bigger in size we can used the method of sieving to separate it out

4. What is sieving? Where is it used?

Answer: Sieving is the process of removing bigger impurities by using a sieve. It is used in the construction sites to remove the stones and pebbles from sand. It is also used in floor mill, to remove bigger impurities like husks and stones from wheat before grinding it.

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

Answer: Sand and water from their mixture can be separated from their mixture, by using the method of sedimentation and decantation or filtration. Pour the sand and water mixture in  a beaker and set aside for sometime. The sand settles down in the bottom of the beaker by sedimentation. Then the water is carefully taken out from the beaker  by the process of decantation or filtration.

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

Answer: Yes. Since sugar and wheat flour are difference in size, it can be separated by sieving. Since sugar particles are bigger in size, it remains in the sieve and wheat flour passes through it.

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

Answer: We can get the clear water from the muddy water by the process of sedimentation and decantation or filtration. Pour the muddy water in a beaker and set aside for sometime. We can see that the mud settles down in the bottom of the beaker by the process of sedimentaion. Then the clear water from the top is carefully removed out by the process of decantation. It is can also be filtered out by using filter paper. 

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) Threshing
(b) filtration
(c) evaporation
(d) sedimentation and decantation

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

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 the ice after dissolving sugar. More sugar can be dissolved, if we add it before adding ice, since the ability of a liquid to dissolve a substance is more when the temperature is more.

CBSE Class 6 Science Chapter 5 Separation of Substances Additional questions

CBSE Class 6 Science 

Chapter 5: Separation of Substances

Additional Questions

1. When method of handpicking is used to separate one substances from another?
2. Why do we separate substances?   
3. What is mean by threshing? When do we use this method of separation? 
4. What is winnowing? When is it used? 
5. When sieving is used to separate substances? Give an example.   
6. What is mean by sedimentation and decantation? 
7. Explain the uses of decantation with examples. 
8. Give two uses of Filtration in daily life. 
9. What is evaporation? 
10. What is mean by condensation?   
11. How we can separate a mixture of sand and salt.  
12. When a solution is said to saturated? How can we increase the saturation of a liquid?

Answers

1. This method of 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.
2. Before we use 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.
3. Thrashing is the process used to separate grain from stalks. In this process, the stalks are beaten to free the grain seeds. It is used to separate the grain seeds, which is difficult to pluck it out like mangoes and guavas
4. 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. The husk particles are carried away by the wind. The seeds of grain get separated and form a heap near the platform for winnowing. 
5. Sieving is used when components of a mixture have different sizes. To remove bigger impurities from floor, we use sieving. Sieving allows the fine flour particles to pass through the holes of the sieve while the bigger impurities  remain on the sieve. 
6. Sedimentation is the process in which the heavier component in a mixture settles when  water is added to it. Decantation is the process of separating the water without disturbing the settled particles.
7.  Decantation is used  to separate insoluble solids and liquids in a mixture. Mud present in the rain water can be separated by the process of decantation. Mixture of oil and water can also be separated by decantation. If a mixture of such liquids is allowed to stand for some time, they form two separate layers. The component that forms the top layer can then be separated by decantation.
8. The method of filtration is used to separate seeds and solid particles when we make juice. When we make paneer at home, the liquid substances is filtered using a fine cloth or strainer.
9. Evaporation is the process of conversion of water into its vapour.
10. Condensation is the opposite process of evaporation. It is the process of conversion of water vapour into its liquid form.
11. Take the mixture of sand and salt in a beaker and add some water to this. Leave the beaker aside for some time. The settled down at the bottom, can be separated by decantation or filtration. Now the boiled the filtered water, the water evaporates and the salt remains in the kettle.
12.  A solution is said to be saturated if it dissolves maximum amount of a substance and cannot dissolve the substance further. The saturation of  a given liquid can be increased by heating.

CBSE Class 6 Science Chapter 5 Separation of Substances Fill in the blanks

CBSE Class 6 Science 

Chapter 5: Separation of Substances 

Fill in the Blanks

1. -------------method is used to separate stones from rice, wheat and other pulses.
2. ------------process is used to separate grains from stalks.
3. Threshing can be done with help of ---------------- and ----------------.
4. The separated husk can be used as --------------. 
5. ------------ is used to separate heavier and lighter components of a mixture by wind or blowing air
6. ----------- is used at construction sites to separate pebbles and stones from sand.
7. ---------------- principle is used for separating a mixture of two liquids that do not mix with each other
8. -------------method is used to separate tea leaves from tea.
9. The dissolved salts from water is removed by the process of -------------.
10. The process of conversion of water vapour into its liquid form is called --------.  
11. ---------------can be used to separate components of a mixture of an insoluble solid and a liquid. 
12. ---------------- process is the opposite of evaporation.

Answers

1. Handpicking
2. Threshing
3. bullocks and machines
4. fodder for cattles
5. Winnowing
6. Sieve
7. Sedimentation and decantation
8. Filtration
9. evaporation
10. condensation
11. Filtration
12. Condensation