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.