NCERT Solutions for Class 6 Science Chapter 5 Separation of Substances

NCERT Solutions for Class 6 Science Chapter 5 Separation of Substances are available here with free PDF. These solutions include answers to all exercise questions given in the NCERT textbook. NCERT solutions for class 6 science Chapter 5 contain various type of questions like match the following, fill in the blanks, MCQ and long answer questions.

All these solutions are prepared by expert teachers with detailed explanations of every important topic. It is important for the students to go through these NCERT solutions to get knowledge of the type of question asked in the chapter.

Class 6 Science Chapter 5 Separation of Substances Questions and Answers PDF

Exercise Questions

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

Answer: When two or more substances are mixed together they form a mixture. Components of a mixture should be separated because some components may not be useful or may spoil the useful component of the mixture.

For example:

  • We used to separate slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses by handpicking method.
  • Rice or pulses are usually washed before cooking. When we add water to these, the impurities like dust and soil particles get separated.

Question 2: What is winnowing? Where is it used?

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

Question 3: How will you separate husk or dirt particles from a given sample of pulses before Cooking?

Answer: Husk or bigger pieces of dirt particles can be removed from a sample of pulses by handpicking.

Question 4: What is sieving? Where is it used?

Answer: Sieving is the process of filtering components of a mixture of different sizes. Sieving allows fine particles to pass through the holes of the sieve, while the bigger impurities remain on the sieve.

Sieving is used in flour mills to separate broken particles of grains from flour. It is also used at construction sites to separate lumps, smaller stones from the mixture of sand and cement.

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

Answer: To separate sand and water from their mixture, we follow the following steps:

  • Leave mixture to stand undisturbed for some time in a container.
  • Sand settles at the bottom of the container. It is called sedimentation.
  • Gently pour the water in another container (called decantation).
  • We may also use filter paper to remove fine particles of sand (called filtration)

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

Answer: Yes it is possible to separate sugar mixed with wheat flour by the following method
(a) Mix sugar and wheat flour in water
(b) stir the solution to allow sugar to dissolve
(c) Now filter the mixture
(d) filtrate contains sugar solution and residue will be wheat flour.

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

Answer: Following steps are required to obtain clear water from muddy water:

  • Allow muddy water to stand undisturbed in a container.
  • After sometime, mud settles at the bottom of the container. This process is called sedimentation.
  • Upper layer is clear water.
  • Pour the clear water gently in another container. This process is called decantation.
  • To remove finer impurities we can filter this water again with the help of filter paper. This process is called filtration.

Question 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
(b) 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

Question 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 sugar before adding ice. Sugar dissolves in warm water more quickly than in cold water. We can dissolve more sugar before mixing ice in water.

Class 6 Science Chapter 5 Separation of Substances Extra Questions

Class 6 Science Chapter 5 Separation of Substances From Extra Questions section includes multiple choice questions (MCQs), short and answer type questions etc. All these questions are very important from examination point of view.

Extra Questions

Multiple Choice Questions (MCQs)

(i) Butter is separated from milk by

(a) sedimentation
(b) filtration
(c) churning
(d) decantation

Answer: (c) churning

(ii) Filtration is a method to separate the components of a

(a) solution
(b) mixture of a liquid and an insoluble substance
(c) both (a) and (b)
(d) pure substance

Answer: (b) mixture of a liquid and an insoluble substance

(iii) Threshing is done by

(a) beating
(b) bullocks
(c) machines
(d) all of these

Answer: (d) all of these

(iv) Which method is used to separate pebbles and stones from sand?

(a) Handpicking
(b) Winnowing
(c) Sieving
(d) Any of these

Answer: (c) Sieving

(v) The components of a solution (say sugar in water) can be separated by

(a) filtration
(b) evaporation
(c) sedimentation
(d) decantation

Answer: (b) evaporation

(vi) Sand from water is separated by

(a) sieving
(b) evaporation
(c) filtration
(d) sedimentation and decantation

Answer: (d) sedimentation and decantation

(vii) The process of conversion of water vapours into liquid is called

(a) condensation
(b) decantation
(c) sedimentation
(d) evaporation

Answer: (a) condensation

(viii) The process of conversion of water into its vapours is called

(a) evaporation
(b) condensation
(c) guttation
(d) transpiration

Answer: (a) evaporation

(ix) A mixture of ammonium chloride and sand is separated by

(a) evaporation
(b) decantation
(c) sublimation
(d) filtration

Answer: (c) sublimation

(x) The property which forms the basis of sieving

(a) difference in weight
(b) difference in colour
(c) difference in shape
(d) difference in size

Answer: (d) difference in size

Short Type Questions and Answers

Question 1. When is handpicking used?

Answer: Handpicking is used to separate undesirable component when present in small
amount.

Question 2. What is threshing? How is it done?

Answer: The process that is used to separate the grain from stalks is threshing. In this process, the stalks are beaten to free the grain seeds. Sometimes, threshing is done with the help of bullocks. Machines are also used to thresh large quantities of grain.

Question 3. Which type of separation is used in cashew nut factories?

Answer: Sieving.

Question 4. Give one example of sieving used in everyday life.

Answer: Separation of barn (choker) from flour.

Question 5. Name some materials that are used as filters.

Answer: Cotton, ceramic, filter cloth, filter paper.

Question 6. Name the process of separating two immiscible liquids.

Answer: By using separating funnel or by decantation.

Question 7. Which substance is used for loading?

Answer: Alum (phitkari).

Question 8. What is the use of alum in loading?

Answer: Alum is used to make the sedimentation faster. Bv adding alum the clay particles settle down rapidly.

Question 9. Which process is used to separate bacteria from water?

Answer: Filtration, by using special filters, i.e., bacteria proof filter.

Question 10. What is decantation?

Answer: Decantation is a process of separating insoluble solids from liquids. A suspension of solid particles in liquid is allowed to stand for some time. Solid particles settle down at the bottom, due to their weight.

Question 11. What is the use of decantation?

Answer: Decantation is used to separate insoluble solids from liquids. Two immiscible liquids are also separated by this process.

Question 12. What is the drawback of evaporation?

Answer: The liquid in the mixture is evaporated off into the air and is not recovered.

Question 13. Name the process to obtain salt from seawater.

Answer: Evaporation.

Question 14. Which types of mixtures are separated by evaporation?

Answer: Evaporation is used to separate solids dissolved in liquid.

Question 15. Describe the method to obtain pure salt from rock salt.

Answer: First, the mixture is crushed and grinded. Water is then added and filtered. Pure salt is collected as filtrate which is heated for evaporation. Water evaporates off and pure salt is left.

Question 16. How will you separate pure water from a solution of salt in water?

Answer: We can separate pure water from a solution of salt in water, by the process of distillation that is by evaporation and followed by condensation.

Question 17. Write opposite process of condensation.

Answer: Evaporation.

Question 18. What do you mean by solubility?

Answer: The maximum mass of a solute that can be dissolved in 100 g of the solvent at any specific temperature is called solubility.

Question 19. Why is water a universal solvent?

Answer: Water can dissolve different kinds of substances. That is why water is commonly called as a universal solvent.

Question 20. What is the effect of temperature on solubility?

Answer: Solubility increases when the increase in temperature takes place.

Question 21. Differentiate between saturated and unsaturated solutions.

Answer: Saturated solution: A solution in which no more solute can be dissolved at a given temperature.
Unsaturated solution: A solution in which more solute can be dissolved at any temperature.

Question 22. During centrifugation, which particles settle down at the bottom?

Answer: Heavy particles settle down at the bottom and lighter particles float at the top of the liquid.

Question 23. Name the method by which you can separate butter from milk.

Answer: Centrifugation.

Question 24. Name the device by which cream can be separated from milk at home.

Answer: A mixer-grinder is a very important device by which cream can be separated from milk.

Question 25. Why does visibility increase after rains?

Answer: After rains, the objects at a distance are seen more clearly, because the fine dust particles that were present in air settle down due to loading by rain drops.

Question 26. What is strainer?

Answer: Wire mesh is commonly known as strainer. For example, while preparing tea, we separate tea leaves from water by using a filter such as wire mesh. Tea leaves are bigger in size than the holes of the mesh.

Long Type Questions and Answers

Question 1. Name the property of the components used for separating the following mixtures:

  1. salt and camphor
  2. wheat and husk
  3. iron fillings and saw-dust
  4. coconut oil and water.

Answer:

  1. sublimation
  2. winnowing
  3. magnetic separation
  4. separating funnel.

Question 2. Mention the methods that can be used for the separation of the following mixtures:

  1. wheat, sugar and husk
  2. rice, gram and iron fillings
  3. sand, Mack gram (urad) and husk.

Answer:
1. Mixture of wheat, sugar and husk.

  • For separating husk from the mixture, we should follow the winnowing method as husk is lighter than other two components.
  • Wheat and sugar can be separated by sieving as they have different sizes.

2. Mixture of rice, gram and iron fillings.

  • For separating iron fillings, we can use a magnet.
  • Rice and gram can be separated either by sieving or by handpicking.

3. Sand, black gram (urad) and husk.

  • For separating sand from the mixture, we can sieve the mixture.
  • Black gram (urad) and husk can be separated by the method of winnowing.

Question 3. Write various methods of separation of compounds from their mixture.

Answer:

  1. Handpicking
  2. Threshing
  3. Winnowing
  4. Sedimentation
  5. Decantation
  6. Filtration
  7. Evaporation
  8. Condensation.

Question 4. How will you Separate a mixture of common salt and chalk powder?

Answer: We know that common salt is soluble in water while chalk is sparingly, soluble. So, on the basis of different solubility, we can separate the common salt and chalk powder as follows:

  • First, some water is mixed with the mixture of common salt and chalk powder, stir the solution well. Filter the solution by using filter paper. On filtering, chalk powder is obtained as a residue on the filter paper and salt solution is obtained.
  • Now filtrate is evaporated and dry common salt is left behind.

Question 5. Match the following items given in Column A with that in Column B:

Column AColumn B
(a) Handpicking(i) Conversion of water vapours into liquids
(b) Threshing(ii) Separating bran from flour
(c) Winnowing(iii) Separating larger size impurities
(d) Sieving(iv) Separating butter from milk
(e) Sedimentation(v) Conversion of water into Us vapours
(f) Evaporation(vi) Separating grains from its stalks
(g) Condensation(vii) Settling of heavier components at bottom
(h) Churning(viii) Separation by wind or by blowing air

Answer:

Column AColumn B
(a) Handpicking(iii) Separating larger size impurities
(b) Threshing(iv) Separating grains from its stalks
(c) Winnowing(viii) Separation by wind or by blowing air
(d) Sieving(ii) Separating bran from flour
(e) Sedimentation(vii) Settling of heavier components at bottom
(f) Evaporation(v) Conversion of water into its vapours
(g) Condensation(i) Conversion of water vapours into liquids
(h) Churning (iv) Separating butter from milk

Question 6. What is filtration?

Answer: The process by which insoluble substance can be separated from a solution, by passing that solution through a porous paper (filter paper) is called filtration.

When one component of a mixture is soluble in water and other component is insoluble in water, the soluble component gets dissolved and insoluble one is separated by filtering the solution.

During filtration, the solid insoluble substance is retained at the filter paper as residue while the liquid free from any suspended matter passes through the filter paper and is collected as filtrate.

Question 7. How is common salt obtained from seawater?

Answer: When seawater is allowed to evaporate in shallow pits, water gets heated by sunlight and changes into water vapour by the process of evaporation leaving behind impure solid salts. Now, the lumps of impure common salt are crushed to get powdered salt. The powdered common salt is dissolved in water to prepare a solution. Now the solution of common salt is filtered to remove insoluble impurities. The clear solution is evaporated by heating to remove the water content to obtain a concentrated solution of common salt. The hot and concentrated solution is allowed to cool. On cooling, crystallization takes place and crystals of pure common salt are obtained.

Question 8. What is the importance of centrifugation? How is it done?

Answer: Centrifugation is the process of separating suspended particles from a liquid by rotating the liquid at a high speed.
The mixture is taken in a closed bottle and rotated at a high speed. The heavy particles settle at the bottom while light particles remain behind. This method is also used to separate cream from milk. Cream collects at the centre and being lighter than milk, it floats at the top of the mixture.

NCERT Solutions for Class 6 Science Chapter 5 Separation of Substances: Important topics

  • Methods of separation
  • Hand-picking
  • Winnowing
  • Threshing
  • Sieving
  • Sedimentation, Decantation and Filtration
  • Evaporation
  • Use of more than one method of separation
  • Can water dissolve any amount of a substance?
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