Here you will get Class 6 Science Chapter 5 Separation of Substances Exercise Solution

NCERT Solutions of Exercise for Class 6 Science Chapter 5 Separation of Substances

Exercise

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

Ans: We need to separate different components of a mixture because it may contain harmful or non-useful substances. Sometimes, we separate even useful components if we need to use them separately.

For Example:

(i) Tea leaves are separated from the liquid with a strainer, while preparing tea

(ii) Milk or curd is churned to separate the butter

2. What is winnowing? Where is it used?

Ans: Winnowing is a method of separating 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

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

Ans: To separate husk or dirt particles from a given sample of pulses, we have to wash it before cooking. When you add water to these, the impurities like husk or dirt particles go into water, which becomes a little muddy. Now the vessel is tilted to pour out the dirty water.

4. What is sieving? Where is it used?

Ans: Sieving is a process in which fine particles of mixture are allowed to pass through the holes of the sieve while the bigger impurities remain on the sieve.

It is used to remove impurities like husk and stones from wheat before grinding it. It is also used to separate pebbles and stones from sand.

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

Ans: Let the mixture of sand and water stand for some times, until you observe some soil settle at the bottom of water. Now, slightly tilt the glass without disturbing the water. Let the water from the top flow into another glass. This is how you will get sand and water separated.

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

Ans: Yes. We can separate sugar mixed with wheat flour by sieving. When we pour this mixture onto sieve, the smaller flour particles pass through the holes of the sieve while the bigger sugar particles remain on the sieve.

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

Ans: Let the muddy water stand for some times, until you observe some soil settle at the bottom of water. Now, slightly tilt the glass without disturbing the water. Let the water from the top flow into another glass. You will observe that water is still muddy, so remaining impurities can be separated by a filtration. Take a filter paper, folded in the form of a cone & fixed onto a funnel. The mixture is then poured on the filter paper. Solid particles in the mixture do not pass through it and remain on the filter. This is how you will obtain clear water.

8. Fill up the blanks

(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.

9. True or false?

(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

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: I will add ice to lemonade after dissolving sugar. It is possible to dissolve more sugar if we add ice to lemonade after dissolving sugar.