RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Rajasthan Board RBSE Class 7 Science Chapter 3 Separation of Substances

RBSE Solutions for Class 7 Science

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

RBSE Class 7 Science Separation of Substances Intext Questions and Answers

Page No 24.

Question 1.
Write the components of mixture that are used in our daily life in the table.
Answer:
Table : Components of mixture that are used in daily life –
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-1

Question 2.
What is the difference between sand and sugar ? When you observe them ?
Answer:
Sand contains different types of particles i.e. soil. gravels, weed. etc. and these are mixed with each other. Hence it is a mixture. While sugar contains only one type of particles, hence sugar is a substance.

Question 3.
If you are given a mix of wheat, barley and corn and asked to segregate the three then what will you do?
Answer:
We will separate the mixture of wheat, barley & corn on the basis of their identification by picking with our hands/hand picking.

Page No 27.

Question 4.
How to remove insoluble impurities from dirty water ?
Answer:
Insoluble impurities are removed from dirty water by filtration method.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Page No 28.

Question 5.
How does separation of butter and butter milk from curd take place ?
Answer:
Curd is rotated in circular direction with the help of chum due to which butter milk being heavier in weight goes downwards while butter being lighter in weight comes upwards and separated out. This process is called centrifugal ion.

Page No 29.

Question 6.
How do we find salt from seawater?
Answer:
To find salt from sea water, water is made to accumulate in small lagoons. Water turns into water vapour with the heat of the sun and salt remains in the lagoons which is separated out. This method of separation is called vaporization.

Page No 30.

Question 7.
After sometime naphthalene balls used for protecting woolen clothes, reduce in size. Why does this happens ?
Answer:
Naphthalene balls directly change into vapour phase from its solid phase by gaining heat energy from woollen clothes. It occurs due to property of sublimation of some substances. Some solids on heating directly get converted into vapours while turn directly into solids on cooling without getting converted into liquid. This process is called sublimation. eg., naphthalene, kapoor,.ctc.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Page No 31.

Question 8.
Why Potash alum is used in dirty water?
Answer:
Potash alum is used in dirty water for separating impurities. Sand particles being heavier settle down at the base of the beaker. Clean water can be separated out through decantation.

Question 9.
How dissolved impurities in water do one separated out ?
Answer:
Dissolved impurities in water are separated out through vapourization and condensation method.

RBSE Class 7 Science Separation of Substances Tex Book Questions and Answers

Choose the most appropriate option –

Question 1.
Which process is used for separating out wheat from impurities –
(a) Winnowing
(b) Magnetic separation
(c) Hand Picking
(d) Threshing
Answer:
(b) Magnetic separation

Question 2.
Which process is used for separating curd from butter –
(a) Distillation
(b) Gentrification
(c) Sieving
(d) Vaporization
Answer:
(c) Sieving

Question 3.
Type of homogeneous mixture –
(a) Mixture of milk and Sugar
(b) Mixture of sand and iron
(c) Mixture of Soil and Water
(d) Mixture of Oil and Water
Answer:
(a) Mixture of milk and Sugar

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 4.
Process of converting vapour into liquid is called –
(a) Vaporization
(b) Compaction
(c) Distillation
(d) Threshing
Answer:
(b) Compaction

Fill in the blanks:

  1. Separating out gram from mixture of Gram and wheat is called …………………………
  2. Conversion of liquid into vapours is called …………………………
  3. Soft drink is an example of …………………………
  4. ………………………… water is used in making medicines.

Answer:

  1. Handpicking
  2. Vaporization
  3. Homogeneous Mixture
  4. Distilled.

Match the following in Column A and Column B.

Question 1.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-2
Answer:

  1. (b)
  2. (c)
  3. (a)
  4. (d)

Short Answer type Questions:

Question 1.
What is Lagoon ?
Answer:
To find salt from sea water, water is made to accumulate in small land of piece. This is known as Lagoon.

Question 2.
Explain homogeneous mixtures with examples.
Answer:
Homogeneous mixture –
Those mixture which two or more components are. present but can not be seen separately are called homogeneous mixtures.
Example:
mixture of water and salt. Water and salt can not be seen separately in this mixture. Another cg. – Air.

Question 3.
What do you mean by filtration ? Explain it with diagram.
Answer:
Filtration – The process of separation of components from a solid or liquid mixture is called filtration. Experiment with diagram – Take a filter paper and fold it to make a cone as given in diagram. Place it inside a funnel. Pour the dirty water on filter paper slowly until 2/3 N part of funnel is filled. We will observe that filter paper will prevent soil granules & pebbles & allows only water to pass through it. This process is know as filtration.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-3
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-4

Question 4.
Differentiate between homo – generous and heterogeneous mixtures.
Answer:
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-5

Question 5.
Describe the method of finding pure salt from impure salt with diagram.
Answer:
Finding pure salt from impure salt. method is as follows –
Take mixture of ammonium chloride and salt in china dish. Place it on a tripod stand and place a funnel over the china dish so that it covers the china dish close the lid of the funnel with cotton. Heat the mixture till while smoke begin to arise. Now stop heating the mixture and let the funnel cool down for sometime. We will see the white substance on the surface of the funnel. This is ammonium chloride and salt remains in the china dish.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-6

Long Answer Questions:

Question 1.
Write the process of separating out sand, salt, iron chips from mixture.
Answer:
For this, we have to use more than one methods –

  1. Magnetic separation method
  2. Sedimentation method
  3. Vaporization method.

1. Magnetic separation method –
First of all we separate iron chips from the mixture. By magnetic separation method. By moving a magnet through the mixture repeatedly. iron chips get separated out from the mixture. Thus non – magnetic substances are separated from magnetic substances by magnetic separation method.

2. Sedimentation Method –
Then remaining sand & salt are separated by sedimentation method. Prepare solution of it. Sand will settle dovn at the base of the beaker. Salt solution is separated out by decantation method.

3. Vaporization method –
Now salt is separated out from solution b vaporization method. Thus, by using above three methods. we can separate out these three components from the mixture.

Question 2.
Explain with diagram any four techniques of separation.
Answer:
Various methods are used to separate components of a mixture. Out of these. four are explained as follows –
1. Winnowing –
Farmers make the grains fall from a certain height in the field. Grains being heavier full nearby while on the other hand impurities being lighter in eight fall away with the flow of wind. This method of separating impurities from mixtures is called winnowing.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-7

2. Centrifugation –
We separate butter and butter milk from curd in our homes. In this method, curd is rotated in circular direction with the help of churn due to which butter milk being heavier in eight goes downwards while butter being lighter in weight comes upwards. This method of separation is called centrifugation.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-8

3. Threshing –
Plants of different pulses and grains are dried in the fields. Simultaneously to separate out the grams. dried plants are beaten on rocks or wooden planks. Separating out the food grains from dried plants is called threshing. Now a days threshing machines arc also used for this purpose.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-9

4. Magnetic Separation Method –
Take a mixture of sand and chips of iron on a piece of paper. Place a magnet near the mixture: Repeat this process again and again. We will see that chips of iron will get attracted to the magnet while sand ill remain unaffected on paper. In this av magnetic substances are separated from non-magnetic substances through magnetic separation.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-10

Question 3.
What is the importance of Separation of Substances ? Explain.
Answer:
Separation of substances is important for following reasons –
1. We can improve the quality. purity capability and utility of a mixture by removing the impurities from the mixture.

2. We can find the ration of different components in a mixture. Like impurities in cement reduces its capability. impurity in gold reduces its shine. Drinking impure water can make us sick. Hence we can say that separating mixture from its components is an important part of our lives. There arc so many methods of separation of components from mixture.

RBSE Class 7 Science Separation of Substances Important Questions and Answers

Objective type Questions:

Question 1.
Those mixtures whose components can be seen separately, are called –
(a) Homogeneous mixture
(b) Heterogeneous mixture
(c) Component mixture
(d) None of these
Answer:
(b) Heterogeneous mixture

Question 2.
The process of Separation of components from a solid or liquid mixture is called –
(a) Distillation
(b) Filtration
(c) Winnowing
(d) Centrifugation
Answer:
(b) Filtration

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 3.
Separating out grains from dried plants is called –
(a) Sedimentation
(b) Cutting
(c) Storage
(d) Threshing
Answer:
(d) Threshing

Question 4.
Conversion of any liquid into its vapour is called as –
(a) Vaporization
(b) Filtration
(c) Winnowing
(d) Condensation
Answer:
(a) Vaporization

Question 5.
How can we separate the mixture of salt and ammonium chloride –
(a) Sublimation
(b) Distillation
(c) Vaporization
(d) None of the above
Answer:
(a) Sublimation

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 6.
When grains with husk are fall from a certain height, husk and other particles get separated out. This separation method is called as –
(a) Threshing
(b) Filtration
(c) Sublimation
(d) None of these
Answer:
(d) None of these

Question 7.
Salt is Separated out from sea water by –
(a) Winnowing
(b) Vaporization
(c) Sieving
(d) Centrifugation
Answer:
(b) Vaporization

Question 8.
Water and oil mixture ¡s –
(a) Heterogeneous
(b) Homogeneous
(c) Soluble
(d) None of these
Answer:
(a) Heterogeneous

Question 9.
By which method, mixture of salt and sand can be separated –
(a) Sublimation
(b) Sedimentation
(c) Magnetic Separation
(d) Filtration
Answer:
(b) Sedimentation

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Fill in the blanks:

  1. ……………….. water is used in making, medicines for injections. (Distilled / heavy)
  2. Conversion of vapour into Liquid is called ……………….. (distillation / condensation)
  3. Separation of each component from a mixture is called as ……………….. (Sieving / Separation)
  4. Separating impurities with the hands is called ……………….. (Hand picking / Sieving)
  5. Salt solution is an example of ……………….. (Homogeneous mixture / Heterogeneous mixture)

Match the Column I with Column II correctly –

Question 1.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-11
Answer:

  1. (b)
  2. (d)
  3. (a)
  4. (e)
  5. (c)

Very short answer type Questions:

Question 1.
What do you mean by mixture ? Write its type.
Answer:
Mixture is made from two or more components / substances. Mixtures are of two types

  1. Homogeneous
  2. Heterogeneous.

Question 2.
Give some examples of mixture.
Answer:
So many examples are of mixture – eg. – air, soft drink, ice-cream, sand, tea, halwa. etc.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 3.
What is separation ?
Answer:
Process of separating out liquids from its components is called Separation.

Question 4.
Mention any two methods of separation ?
Answer:

  1. Sieving
  2. Magnetic separation method.

Question 5.
Name the method of Separation using filter paper.
Answer:
Filtration.

Question 6.
What is vaporization ?
Answer:
Conversion of liquid phase into vapour phase is called vaporization.

Question 7.
What is condensation ?
Answer:
Conversion of vapour phase into liquid phase is called condensation.

Question 8.
How sand is separated from dirty water?
Answer:
Sand is separated from dirty water by using filter paper.

Question 9.
What type of mixtures are separated by hand-picking method ? Give example.
Answer:
Gravels, Soil and other impurities arc separated from wheat. barley rice and pulses by hand-picking method.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 10.
What type of mixtures are separated by sieving method ? Give one example.
Answer:
Husk and other impurities arc separated from flour by sieving separation method.

Question 11.
What type of mixture are separated by centrifugation method ? Give one example.
Answer:
Butter and butter milk arc Separated by churning in centrifugation method.

Question 12.
How grains are separated out from their dried plants ?
Answer:
By Threshing method.

Question 13.
Name the method of separation of minor impurities from grains with the help of suup?
Answer:
It is called Winnowing.

Question 14.
Separation of magnetic substances from non-magnetic substances is called as?
Answer:
Magnetic separation method.

Question 15.
Illustrate Sublimation with equation.
Answer:
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-12

Question 16.
What is distillation ?
Answer:
Process of separating out liquid with through vaporization & condensation is called distillation.

Question 17.
What is sedimentation ?
Answer:
Settling down of heavier impurities present in the mixture is called Sedimentation.

Short answer type Question:

Question 1.
Is Separation of components of a mixture necessary in daily life ?
Answer:
Yes. Separation of components of a mixture is necessary in daily life. We can improve the quality, purity capability and utility of a mixture by removing the impurities from the mixture. It is also possible to find the ration of different components in a mixture. Thus. Separating mixture from its components is an important part of our lives. Eg. Purification of impure water.

Question 2.
Explain the process of threshing with diagram.
Answer:
Threshing – Plants of different pulses and grains are dried in the fields. Simultaneously to separate out the grains, dried plants are beaten on rocks or wooden planks Separating out the food grains from dried plants is called threshing. These days threshing machines is also used for this purpose.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-13

Question 3.
What is sublimation ?
Answer:
Some solids on heating directly get converted into vapours while turn directly into solids on cooling without getting converted into Liquid. This process is called Sublimation.

Question 4.
To find salt from sea water, why water is made to accumulate in small Lagoons ?
Answer:
To find salt from sea water. water is made to accumulate in small Lagoons. By Lagoons. water is collected in small parts having smaller surface area. It makes sea water to evaporate faster and easily. Lagoons helps in making heaps of salt at certain places.

Question 5.
What are the methods of separation of components from mixture of substances?
Answer:
Following arc the methods of separation of components of mixtures –

  1. Hand picking
  2. Sieving
  3. Filteration
  4. Winnowing
  5. Centrifugation
  6. Threshing
  7. Vaporization
  8. Magnetic Separation
  9. Sublimation
  10. Sedimentation & Decantation
  11. Distillation. etc.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Question 6.
Comment on the Hand picking method of Separation.
Answer:
Handpicking – In wheat. rice, pulses. many impurities like gravels, soil and other impurities are mixed: These impurities are present in less quantity. These arc different in colour & shape from heat, rice and pulses. These impurities are separated with the hands. This method is called hand picking.

Question 7.
Comment on Sieving in short.
Answer:
Sieving – At the construction site. gravels & pebbles are separated Out from sand with the help of sieves. This process is called sieving. Flour is also sieved so that husk and other impurities remain in the sieve and we get pur flour. This process is called sieving.

Question 8.
Why Winnowing is required with the help of Suup?
Answer:
Method of separating minor impurities from grains with the help of Suup is called Winnowing. Farmers make the grains fall from a certain height in the fields, Grains being heavier fall nearby while on the other hand impurities being lighter in weight fall away with the flow of wind.

Question 9.
Why butter comes upper and butter milk at lower on churning curd?
Answer:
Curd is rotated in circular direction with the help of churn due to which butter milk being heavier in weight goes downwards while butter being lighter in weight comes upwards. This process is called centrifugation.

RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances

Essay type Questions:

Question 1.
What types of mixtures are? Describe with an experiment.
Answer:
Types of Mixtures Mixtures arc classified in two types based on nature of substances –

  1. Homogeneous mixtures
  2. Heterogeneous mixtures

1. Homogeneous Mixture –
Those mixtures in which two or more components are present but can not be seen separately are called homogeneous mixtures.

Example:
Mixture of salt in water. Experiment – Take a glass half filled with water and add a teaspoon of salt in it and stir. Salt will completely dissolve in water. Salt and water can not be seen separately in this mixture. So it is a homogeneous mixture.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-14

2.Heterogeneous Mixture –
Those mixtures in which its components can be seen separately are called heterogeneous mixtures.
Examle:
Mixture of water & oil.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-15

Experiment –
Take some water in a beaker, Add a teaspoon of groundnut oil or mustard oil in it and stir. We will observe two separate layers of water and oil in the beaker. Hence, it is a Heterogeneous mixture.

Question 2.
Explain the following methods of separation with diagram –

  1. Vaporization
  2. Sedimentation & Decantation.

Answer:
1. Vaporization –
Conversion of any liquid into its vapour is called vaporization.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-16
Experiment –
Take a china dish. Fill it half with water. Put a teaspoon of salt in it and stir, Nos heat the water. After sometime we observe that all the water converts into vapour and only salt remains in the china dish. This is vaporization method of semarating mixtures.

2. Sedimentation and Decantation –
Settling, do n of heavier impurities present in the mixture is called sedimentation. Transferring of sedimentated mixture carefully without stirring into another beaker is called decantation, This is also a method of separation of mixtures.

Experiment –
Take a glass beaker. fill it half with water. put a teaspoon of salt in il and stir. We will observe that sand will settle down at the base of the beaker. This is sedimentation. Now we decant this water in another beaker. It is decantation.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-17

Question 3.
Explain the method of finding salt from sea water with diagram.
Answer:
Salt is obtained from sea water by vaporization method. In this method. water is made to accumulate in small Lagoons. Water turns into water vapour with the heat of the sun and salt remains in the lagoons.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-18

Question 4.
What is sublimation ? Explain it with experiment.
Answer:
Some solids on heating directly get converted into vapours while turning directly into solids on cooling without getting converted into liquid. This process is called sublimation. We can separate mixture of salt and ammonium chloride through sublimation.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-19

Experiment –
Take mixture of ammonium chloride and salt in china dish. Place it on a tripod stand and place a funnel over the china dish. Close the lid of the funnel with cotton. Heat the mixture till white smoke appears. Now stop heating the mixture and let the funnel cool down for some time. We will see the white substance on the surface of the funnel. This is ammonium chloride and salt remains in the china dish.

Question 5.
Describe the distillation method of separation with diagram.
Answer:
Method of separating out liquid with through vaporization & condensation is called distillation. Experiment – Take some water in a kettle and bring it to heat. Now take some ice on a metal plate. Keep the metal plate just above the valve of the kettle.

All the water in the kettle gets converted into vapours. Conversion of liquid into vapour is called vaporization. Impurities after remain in the Kettle. When steam comes in contact with the chilled plate. then it gets converted into liquid. This liquid gets condensed in the beaker drop b drop. Conversion of vapor into liquid is called condensation.
RBSE Solutions for Class 7 Science Chapter 3 Separation of Substances-20

Question 6.
How will you separate the components of following mixtures using separating methods –

  1. Mixture of Naphthalene and salt.
  2. Mixture of sand and salt.
  3. Mixture of baking soda and water.
  4. Mixture of mustard oil and water.
  5. Mixture of sand and iron chips.

Answer:

  1. Mixture of Naphthalene and salt can be separated by sublimation method.
  2. Mixture of sand and salt can be separated by sedimentation and vaporization method.
  3. Mixture of baking soda and water can be separated b vaporization method.
  4. Mixture of mustard oil and water can be separated by filtration method.
  5. Mixture of sand and iron chips can be separated by magnetic separation method.

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