NCERT Class VI Science Solutions: Chapter 5 – Separation of Substances Part 4

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LONG ANSWER QUESTIONS

Question 16:

Both Sarika and Mohan were asked to make salt solution. 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.

  1. How would they make salt solutions?

  2. Who would be able to prepare saturated solution?

Answer:

  1. They will mix salt with water to make salt solution. Hence, Sarika will make a better salt solution.

  2. Saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amount of that substance will appear as a precipitate. Mohan’s solution would be saturated because in Mohan’s case some salt would remain undissolved and settle at the bottom of the glass.

Question 17:

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.

Answer:

  1. Filtration using muslin cloth.

  2. Swirl with alum and leave water undisturbed for some time.

  3. The clear liquid above the impurities is another container (Decantation).

  4. Boil for 10 minutes in covered pan and lid.

  5. Cool, filter and now it is fit for drinking.

Question 18:

Read the story titled “WISE FARMEW” 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 lie 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/handpicked 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?

Answer:

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

They got a good price as they used appropriate methods of separation to get good quality of flour.

Question 19:

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.

As images for Mixture by giving an activity

Mixture by Giving an Activity

As images for Mixture by giving an activity

Answer:

  1. Decantation - to separate oil.

    Image of Decantation

    Image of Decantation

    Image of Decantation

  2. Filtration - to separate sand.

    Image of Filtration.

    Image of Filtration.

    Image of Filtration.

  3. Evaporation - to separate salt.

    Image of Evaporation

    Image of Evaporation

    Image of Evaporation

Question 20:

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

Answer:

Iron nails - hand picking/magnet.

Oil – decantation.

Salt, water - evaporation and condensation.