NCERT Class 6 Science Chapter 3 Separation Of Substances Question And Answers

NCERT Class 6 Science Chapter 3 Separation Of Substances Long Question And Answers

Question 1. When separating sand and sawdust or powdered leaves, do both components fall in the same place?
Answer: When sand and sawdust are separated by winnowing, sawdust falls far away from the sand. This is because sand is heavy, while sawdust is light.

Question 2. Which method of separating tea leaves from prepared tea is better, decantation or filtration?
Answer: Tea leaves are better separated from prepared tea using the filtration method. It is because if the decantation method is used, it helps a little, but we still get a few leaves in our tea.

Read and Learn More Class 6 Science Question And Answers

Question 3. Many substances dissolve in water and form a solution. What happens if we go on adding more and more of these substances to a fixed quantity of water?
Answer: If we go on adding more and more of this substance to a fixed quantity of water, some of it remains undissolved in the solution and settles at the bottom of the vessel. This is called a saturated solution.

Question 4. What is sieving? Where is it used?
Answer: Sieving is a method by which fine particles are separated from bigger impurities by using a sieve. It is used in a flour mill, our homes, and at construction sites. In a flour mill, impurities like husk and stones are removed from wheat before grinding. At construction sites, pebbles and stones are removed from sand by sieving.

Question 5. 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 sieving. The size of sugar particles is larger than that ofthe wheat flour. So, sugar will stay on a sieve and wheat flour will pass through the holes of the sieve.

Question 6. How will you separate sand and water from their mixture?
Answer: We will separate sand and water from their mixture by the process of sedimentation and decantation. Sedimentation During this process, we leave the mixture for some time. Heavier sand gets settled down at the bottom.

Decantation After the sedimentation process, water is poured into another vessel, and sand is left undisturbed in the first vessel. Thus, sand and water will be separated from their mixture.

Question 7. How would you obtain clear water from a sample of muddy water?
Answer: We will obtain clear water from a sample of muddy water by the process of filtration.

In this process, we use a piece of cloth to filter muddy water. Because in a piece of cloth, small holes or pores remain in between the woven threads. These pores in a cloth can be used as a filter.

If the water is still muddy, impurities can be separated by a filter paper that has even smaller pores.

A filter paper folded in the form of a cone is 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 paper and in this way, clear water is obtained.

Question 8. 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 ice to lemonade after dissolving sugar. Without ice, sugar dissolves easily in lemon juice because solubility depends on the temperature. When the temperature is high, then more sugar can be dissolved. After mixing ice, it gets cooled down so less sugar will dissolve in it.

Question 9. 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 teaspoonful of salt and half a glass of water.

1. How would they make salt solutions?
2. Who would be able to prepare a saturated solution

Answer:

They will mix salt with a certain amount of water to make a salt solution.

Saturation is a point at which no more substances can be dissolved in the solvent and the substance gets settled down. As Mohan has more quantity of salt than Sarika, hence, he would be able to prepare a saturated solution.

Question 10. 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? Tub, muslin cloth, gas stove, thread, alum, pan, and lid of the substance.
Answer: Paheli can make this water fit for drinking by working on the following sequence

At first, she needs to pour the water through a muslin cloth for filtration.

Next, the water has to be heated in a container on a gas stove until it vaporizes. The vapors are allowed to come in contact with a cold lid so that condense back into water which will be collected in a tub. Impuritiesifany will remain behind in the container.

Then she has to hang a piece of alum with a thread and submerge it in the water, keeping it undisturbed for some time. This allows the impurities to settle down as sediment.

Next, she has to pour off the undisturbed water in a tub by decantation.

Now, the water is fit for drinking.

Question 11. Read the story titled ‘Wise Farmer’ and tick the correct option from the underlined section to complete the story. A farmer was

1. Sad/happy to see his healthy wheat crops ready for harvest. He harvested the crops and left them under the
2. Sun/rain to dry the stalks. To separate the seeds from the bundles of the stalk, he
3. Handpicked/threshed them. After gathering the seed grains, he wanted to separate the stones and husk from them. His wife
4. Winnowed/ threshed them to separate the husk and later
5. Sieved/ handpicked to remove stones from it. She grounded the wheat grains and
6. Sieved/filtered the flour. The wise farmer and his wife got a good price for the flour. Can you tell me why?

Answer:

1. Happy
2. Sun
3. Threshed
4. Winnowed
5. Handpicked
6. Sieved

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

Question 12. You are provided with a mixture of salt, sand, oil, and water. Write the steps involved in the separation of salt, sand, and oil from the mixture by giving an activity along with the diagram.
Answer: In the solution of salt, sand, oil, and water. Oil, being lighter will float on the solution forming a distinct layer, slowly oil is allowed to flow into another container and is separated from the water. This process is called decantation. Now, we are left with salt, sand, and water, to separate this.

Question 13. Pragati was helping her mother in the making of butter. She was amazed to see how easily the butter got separated from milk with the help of a churner.

1. What is the process that is being used above?

1. Grinding
2. Mashing
3. Churning
4. Threshing

Answer: 3. Churning

2. The principle behind the process of churning is

1. Lighter particles of a solid get separated from liquid
2. Heavier particles get settled at the bottom
3. Heavier particles form heaps and lighter particles get swept away by the wind
4. Particles of different sizes get separated

Answer: 1. Lighter particles of a solid get separated from liquid

Question 14. Saroj collected muddy water from a pond. He separated the water from the mud in three steps as shown in the pictures below.

1. Which separation method did Saroj use at each step? Select the correct row

Answer: 1. Evaporation Sedimentation Decantation

2. Which of these properties did Saroj use to separate mud from water?

1. It floats on water
2. It dissolves in water
3. Water turns cloudy due to mud
4. It is heavier than water

Answer: 2. It dissolves in water

Question 15. Nidhi was doing an activity at home. She dissolved some sugar in a glass of water. Later she realised she had to add salt and not sugar. She wants to use the same water. Answer the following questions to help Nidhi with her activity.

1. She can remove sugar from water by
2. Filtering and then evaporating it
3. Condensing and then evaporating it
4. Evaporating and then condensing it
5. Filtering and then condensing it

Answer: 1. Ice water

Water can be separated from sugar solution by first evaporating the water and then condensing it in another vessel to be used again with salt

2. In which of the following added sugar would be dissolved the least?

1. Tap water
2. Filtered water
3. Ice water
4. Boling water

Answer: 2. Filtered water

Ice water has the lowest temperature among all and hence would dissolve less amount of sugar as solubility decreases with a decrease in the temperature.

Question 16. Two beakers A and B are shown below. The components of each have been labeled.

Paheli wants to mix the components of A and B beakers. However, she wants to first separate as many components as possible. Answer the following questions for her activity.

The order of separation of components from beaker A would be

1. Oil layer > water = sand
2. Sand = water > oil layer
3. Sand > oil layer > water
4. Water > oil layer > sand

Answer: 1. Oil layer > water = sand

The oil layer rests on the top of the solution hence it should be removed first. Sand is removed either by decantation or filtration. Hence, both are collected together separately. The correct order is Oil layer > water = sand.

Paheli can remove layers of oil by

1. Filtration
2. Decantation
3. Handpicking
4. Evaporation

Answer: 2. Decantation

Decantation is the process used to remove a layer of oil from the water-sulf solution as it forms a separate layer on top.

Question 17. Ashraf’s grandmother is a diabetic patient. Her doctor advised him to control her sugar level by taking less sugar and less fat content in her diet. So, she always prefers to take lassi instead of milk. Ashraf asked her mother when she explained the process of making lassi by removing cream from the curd. She told him this method is known as churning. Read this passage and answer the following questions.

1. Explain the process of churning.
2. What is the purpose of this method?
3. What values are shown by Ashraf?

Answer:

1. The process of separation of the lighter particles of a solid from a liquid is known as churning. It is also known as centrifugation.
2. The purpose of churning is to remove butter or cream from the curd or milk. So in lassi, there is less fat content as compared to milk.
3. Ashraf is a curious and intelligent boy.

Question 18. Rohit and Raman are best friends. They study in different classes, but in the same standard, Class 6. One day, they were playing in the school. They were throwing sand on each other. Suddenly, Raman asked Rohit if we mix salt in sand, then how will you separate the mixture of sand and salt? Rohit was quite intelligent, his science teacher had completed the chapter Separation of Substances last week. So, he immediately explained the method of separation. Rohit told him that his teacher had shown this activity in the class and the same method is applicable for the separation of the mixture of sugar and sand.

Read the passage carefully and answer the following questions.

1. How is a mixture of sand and salt separated?
2. Name the method(s) that are applicable in the separation of this mixture.
3. What values are shown by Rohit?

Answer:

1. This is done as follows
2. Some water is added to the mixture of sand and salt in a beaker and stirred. Salt dissolves in water to form a salt solution, whereas sand remains undissolved. It is then filtered.
3. On filtering, sand is obtained as a residue on the filter paper, and salt solution is obtained as a filtrate.
4. The filtrate is evaporated and pure salt is left behind.
5. The mixture of sand and salt has been separated into its components, i.e. sand and salt by doing two methods
6. Filtration
7. Evaporation
8. Rohit is a knowledgeable and intelligent boy

Question 19. A construction worker poured a bag full of sand on the slanting sieve. All the sand particles filtered through the pores and the dust particles, stones, pebbles, and husk remain Name the process described above and state its principle.

1. Why is it necessary to remove pebbles and dust particles from sand used for construction?
2. You have been given a glass of muddy water, an empty glass, and a muslin cloth. Describe a method to obtain clean water.
3. Identify the method of separation used to
4. Separate chaff from the grain.
5. Separate tea leaves from the water.

Answer:

1. The process used above is sieving. Principle – A mixture of components having different sizes gets separated with the help of a sieve
2. A sieve has fine pores in it which lets the small-sized components pass through but holds back larger ones. Sand is sieved so that it can be used for construction work without any impurities.

Question 20.

1. You have been given a glass of muddy water, an empty glass, and a muslin cloth. Describe a method to obtain clean water
2. Identify the method of separation used to
3. Separate chaff from the grain.
4. Separate tea leaves from the water.

Answer:

1. Filtration is done to obtain clean water from a glass of muddy water.
2. Winnowing
3. Filtration

Question 21. 

1. A group of students were given a salt solution and were asked to separate the respective components. They set up the apparatus as shown in the given figure.
2. Name the solute and solvent for the given solution.
3. Identify the processes for which the apparatus has been set up in the given figures.
4. Identify the error in the set-up of the apparatus for the separation of a salt solution.

Answer:

1. Solute-salt, solvent-water
2. Filtration, condensation.
3. Salt cannot be separated from water by filtration.

Question 22. Anu adds sugar and salt to two separate glasses of water. She stirs the mixture in each glass every time she adds salt or sugar to it.

She notes her findings in a table

1. What can Anu conclude from her activity?
2. Sugar and salt dissolve equally in water
3. Sugar is more soluble than salt in water
4. Stirring helps in dissolving all substances in a liquid
5. Sugar forms a saturated solution in water, but salt does not
6. Anu used two spoons of the same size to add sugar and salt to the water. What else did Anu need to keep the same for her activity?
7. Anu repeats the activity using hot water. Will the results in the table remain the same? Explain your answer.
8. Which of these processes could be used to separate the sugar dissolved in the glass of water?
   1. Filtration
   2. Evaporation
   3. Condensation
   4. Sedimentation

Answer:

1. Sugar is more soluble than salt in water
2. Anu needs to keep the amount of water fixed to determine the solubility of a substance.
3. No, results would not remain the same as temperature has a direct effect on solubility. With the increase in temperature, the solubility of both sugar and salt increases, but in different amounts.
4. Evaporation

Question 23. A beaker contains a mixture of salt, sand, and water. The mixture is filtered using filter paper.

1. What is substance X?
2. Write a single separation method by which water can be separated from a mixture of salt, sand, and water.

Answer:

1. The substance ‘X sand as the process of filtration is used to separate insoluble solids, i.e. sand from its liquid mixture.
2. By evaporating the mixture of salt, sand, and water, water will evaporate and separate. But sand and salt will remain in the vessel.

NCERT Class 6 Science Chapter 3 Separation Of Substances Short Question And Answer

Question 1. What is the principle of threshing?
Answer: Threshing is the method of separation based on the fact that the stalk of the crops and the chaff are soft materials, whereas the grains themselves are hard. Being soft, stalk and chaff can be broken into pieces on beating, but the grains remain unaffected.

Question 2. When a hot saturated solution is heated, crystals will be formed. Is It correct? If not, write the correct statement.
Answer: It is not correct as when a hot saturated solution is cooled, crystals will be formed.

Question 3. Name and describe briefly a method that can help separate a mixture of husk from grains. What is the principle of this method? NCERT Exemplar
Answer: Winnowing is used to separate grains from impurities like husk by dropping them vertically from a height. All light impurities are separated by a blowing air or wind and hence, husk from grains are separated easily.

Question 4. You have been given a solution of substance X. How will you test whether it is saturated or unsaturated? Give one factor affecting the solubility of a substance in solution.
Answer: When no more substance can be dissolved in the solution at a given temperature then the solution is saturated. Temperature affects the solubility of the substance.

Question 5. What happens when sand and powdered leaves are dropped at the same place in the wind?
Answer: Since, sand is heavier, while powdered leaves are lighter. When we drop these at the same place, blowing wind separates them as sand falls near that place vertically, while leaves are blown away. This process is known as winnowing.

Question 6. The best way to carry out the filtration of the mixture of water and sand is to use filter paper, not cloth, why?
Answer: Since, clothes may have small holes, but filter papers do not have any holes. It has very fine pores in it. Hence, sand particles settle down on the filter paper, while water after pouring reaches the bottom of the vessel.

NCERT Class 6 Science Chapter 3 Separation Of Substances Assertion-Reason Questions

Question 1. The following questions consist of two statements. Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of A
3. A is true, but R is false
4. A is false, but R is true

1. Assertion (A) Husk and flour can be separated by the process of sieving.
Reason (R) Sieving is used when the particle sizes of the two components in the mixture differ.
Answer: Both A and R are true and R is the correct explanation of A.

2. Assertion (A) Evaporation can be used to separate a solid (like salt, or sugar) dissolved in a liquid. Reason (R) Evaporation is the process in which a solid gets converted to vapor.
Answer: A is true, but R is false. R can be corrected as Evaporation is the process in which liquid gets converted to vapor form and thus this process can be used to separate solids dissolved in a liquid.

3. Assertion (A) A substance gets dissolved more in hot water as compared to cold water. Reason (R) Solubility decreases with an increase in temperature.
Answer: A is true, but R is false. R can be corrected as Solubility increases with an increase in temperature

Question 2. Direction The following questions consist of two statements. Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of
3. A is true, but R is false
4. A is false,

1. Assertion (A) The mixture of mud and water can be separated by using the process of filtration. Reason (R) The process of separating insoluble substances from a liquid using a filter is called filtration.
Answer: Both A and R are true and R is the correct explanation of A

2. Assertion (A) Filtration is used to separate chalk powder from water. Reason (R) Chalk powder is insoluble in water.
Answer: Both A and R are true and R is the correct explanation of A

NCERT Class 6 Science Chapter 3 Separation Of Substances Fill In The Blanks

1. The method of separating the seeds of paddy from its stalks is called Thereshing

2. 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

3. Salt is obtained from seawater by the process of Evaporation

4. 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 Sedimentation And Decantation

5. Insects can be separated from wheat by Handpicking

6. Crushing paddy under Cattle’s feet to separate grains is called Threshing

7. Husk from wheat flour is generally removed by Sieving

8. Slanting sieve Used at construction sites to separate pebbles and stones from sand.

9. The process of settling heavier particles in a solution is called Sedimentation.

NCERT Class 6 Science Chapter 3 Separation Of Substances True Or False.

1. A mixture of milk and water can be separated by filtration. False, we cannot separate the mixture of milk and water by filtration because milk is completely soluble in water.

2. A mixture of powdered salt and sugar can be separated by the process of winnowing. The false, winnowing process is used to separate heavier and lighter components of a mixture. Here, particles of size sugar and salt are almost of same size.

3. Separation of sugar from tea can be done by filtration. False, sugar cannot be separated from tea by filtration because sugar is completely soluble in tea.

4. Grain and husk can be separated by the process of decantation. False, grain and husk are separated by the process of winnowing.

5. Separation of components of a mixture is a useful process. True

6. A mixture of iron filings and rice flour can be separated by handpicking. False, iron filling can be separated from rice flour using a magnet

7. A mixture of wheat grains and rice flakes can be separated by winnowing. True

8. A mixture of oil and water can be separated by filtration. False, a mixture of oil and water can be separated by decantation

9. A mixture of tea leaves and milk can be separated by filtration. True

NCERT Class 6 Science Chapter 3 Separation Of Substances Match The Columns

Question 1. Match the following separation processes with their purposes and the way separated components are used.

Answer: The correct match is 1.(b)-(i), 2.-(a)-(iii),3.-(c)-(ii)

Question 2. Match the Column 1 with Column 2

Answer: A-3, B-4,C-5,D-2, E-1

Question 3. Match The Column 1 And Column 2

Answer: A-3,B-1,C-5,D-4, E-2