Chapter 5: Separation of Substances

Q1Written answer

Both Sarika and Mohan were asked to make salt solutions. Sarika was given a teaspoonful of salt and half a glass of water, whereas Mohan was given twenty teaspoons full of salt and half a glass of water.

(a) How would they make salt solutions?

(b) Who would be able to prepare a saturated solution?

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Worked solution

Ans: Both Sarika and Mohan will continually stir the salt into the water. There will be a solution.

Ans: because Mohan has more salt than water, his solution will be saturated. Some of the salt will not dissolve.

Q2Written answer

Paheli was feeling thirsty but there was only a pot of water at home which was muddy and unfit for drinking. How do you think Paheli would have made this water fit for drinking if the following materials were available to her.

Alum, tub, muslin cloth, gas stove, thread, pan and lid.

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Worked solution

Ans: Paheli would first filter the murky water via muslin cloth.

She'd then tie a bit of alum to a thread, dunk it in water, and leave it alone for a while.

She'll notice that the contaminants have sunk to the bottom of the container and that the water may now be emptied out.

Boil the water that has been emptied out, then let it cool before filtering it.

She is now able to swallow the water.

Q3Written answer

Read the story titled “WISE FARMER” and tick the correct option to complete the story.

A farmer was sad/happy to see his healthy wheat crop ready for harvest. He harvested the crops and left it under the sun/rain to dry the stalks. To separate the seeds from the bundles of the stalk he handpicked/threshed them. After gathering the seed grains he wanted to separate the stones and husk from it. His wife winnowed/threshed them to separate the husk and later sieved/hand-picked to remove stones from it. She ground the wheat grains and sieved/ filtered the flour. The wise farmer and his wife got a good price for the flour. Can you tell why?

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Worked solution

Ans: Happy, sun, threshed, winnowed, hand-picked, sieved.

Because they employed acceptable procedures to obtain good quality flour, the farmer and his wife were able to sell the flour for a good price

Q4Written answer

You are provided with a mixture of salt, sand, oil and water. Write the steps involved for the separation of salt, sand and oil from the mixture by giving an activity along with the diagram.

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Worked solution

Ans: We can separate salt, sand, oil and water with the following method-

(a) Decantation: Because oil floats on water (it is insoluble in water), it is simple to decant.

(b) Filtration: Filter the mixture to separate the sand from the water (sand is insoluble in water), leaving just the salt solution.

(c) Evaporation: Salt can be separated from a solution by evaporating it.

Q5Written answer

A mixture of iron nails, salt, oil and water is provided to you. Give stepwise methods to separate each component from this mixture?

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Worked solution

Ans: Iron nails can either be hand-picked or attracted towards the magnet. Oil can be removed by decantation method or using a separatory funnel. Salt solution can be evaporated. In this, the water will evaporate and only salt will be left in the pan.

An Overview of NCERT Exemplar for Class 6 Science Chapter 5 Separation of Substances

We use a process that converts a mixture or solution of chemical substances into two or more distinct product mixtures which is known as separation. When the separation process is over, at least one substance out of a mixture is richer as compared to other constituents in one or more of the source mixture's constituents. In some cases, it happens that due to separation the mixture is divided fully into pure constituents.

Substances are mostly available in mixtures. A few substances are available in pure form. Hence, we need to separate the useful substance from the mixture by using some methods.

Need of separation

There are various kinds of impurities present in the Substances. So the separation process is needed to remove the impurities and get two or more products out of the mixture.

Separation of substances can be carried out under two conditions

Dry conditions
Wet conditions

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