PSEB 6th Class Science Solutions Chapter 5 Separation of Substances

Punjab State Board PSEB 6th Class Science Book Solutions Chapter 5 Separation of Substances Textbook Exercise Questions and Answers.

PSEB Solutions for Class 6 Science Chapter 5 Separation of Substances

Science Guide for Class 6 PSEB Separation of Substances Intext Questions and Answers

Think and Answer (Textbook Page No. 41)

Question 1.
How will you separate rotten tomatoes from a basket of tomatoes?
Answer:
By handpicking.

Question 2.
How will you separate green grapes from black grapes?
Answer:
By handpicking.

Think and Answer (Textbook Page No. 43)

Question 1.
What is the role of wind in winnowing ?
Answer:
The wind blows away the lighter particles.

Question 2.
Can you separate mixture of channa dal and moong dal by winnowing ?
Answer:
No. this mixture cannot be separated by winnowing.

Question 3.
Can you separate a mixture of salt and flour with sieve? Why or Why not ?
Answer:
No. this mixture cannot be separated with sieve. This is because the particles of salt and flour have almost same sizes.

Think and Answer (Textbook Page No. 45)

Question 1.
You are provided with a solution of chalk powder and water in a beaker. Keep the beaker undisturbed for some time. What will you observe ? Name the process.
Answer:
On keeping the beaker undisturbed for some time we observe that the chalk will settle at the bottom in the form sediment. This process of settling insoluble particles at the bottom is called sedimentation.

Think and Answer (Textbook Page No. 46)

Question 1.
Your father asked you to bring fresh orange juice from market. Do you observe the strainer used to separate pulp and seeds from the juice ? Which strainer is the best for this purpose ? Whether tea strainer, filter paper, muslin cloth or strainer with large holes can be used for this purpose.
Answer:
The best strainer will be that which has holes smaller than the sizes of the pulp particles and seeds. Out of the given strainers we can use muslin cloth. We can also use tea strainer and filter paper but these will do the separation slowly. Strainer with large holes will not separate the pulp.

Think and Answer (Textbook Page No. 47)

Question 1.
Name the process involved in preparation of “Khoya” from milk.
Answer:
We prepare “khoya” from milk by the process called evaporation.

Think and Answer (Textbook Page No. 48)

Question 1.
Name the process by which water changes to vapours.
Answer:
The process by which water changes to vapours is called evaporation.

Question 2.
Name the process by which vapours changes to water.
Answer:
The process by which vapours change to water is called condensation.

PSEB 6th Class Science Guide Separation of Substances Textbook Questions and Answers

1. Fill in the Blanks:

(a) Filtration process is helpful in separating an insoluble …………… from a ……………….
Answer:
insoluble, solution

(b) Small pieces of stones can be removed from rice by ……………… method.
Answer:
hand picking

(c) ……………… is used to remove husk from flour.
Answer:
Winnowing

(d) The method in which stalks are beaten to separate the grains is called ………………..
Answer:
threshing

(e) ……………… is the process of pouring out the liquid present on top layer without disturbing
the sediments below.
Answer:
decantation

2. Write True or False:

(a) Sieving is used when the component of mixture has different sizes.
Answer:
True

(b) Process of converting liquid to vapours is called condensation.
Answer:
False

(c) A mixture of salt and flour is separated by handpicking.
Answer:
False

(d) Threshing is a process of separating grains from stalks.
Answer:
True

3. Match the Column A with Column B:

Column A	Column B
1. Separating salt from water	(a) condensation
2. Heavier particles settle down	(b) winnowing
3. Separating different components by blowing wind or air	(c) evaporation
4. Conversion of vapour into liquid	(d) Sedimentation

Answer:

Column A	Column B
1. Separating salt from water	(c) evaporation
2. Heavier particles settle down	(d) Sedimentation
3. Separating different components by blowing wind or air	(b) winnowing
4. Conversion of vapour into liquid	(a) condensation

4. Choose the Correct Answer:

Question (i)
Which method is used to separate heavier and lighter components in a mixture by wind ?
(a) Hand picking
(b) Threshing
(c) Sieving
(d) Winnowing.
Answer:
(d) Winnowing

Question (ii)
Formation of water droplets on the outer surface of glass containing ice cold water is because of:
(a) Evaporation of water from glass
(b) Condensation of atmospheric water vapours.
(c) Water that seeped out from glass
(d) Evaporation of atmospheric water vapours.
Answer:
(b) Condensation of atmospheric water vapours.

Question (iii)
You must have seen your mother taking out fine gravels from rice. Which method can be used to separate pebbles from rice ?
(a) Handpicking
(b) Decantation
(c) Evaporation
(d) Sedimentation.
Answer:
(a) Handpicking

Question (iv)
We need to separate one substance from mixture because :
(a) To separate two different but useful components
(b) To remove undesirable substances
(c) To remove harmful substances
(d) All the above.
Answer:
(d) All the above.

5. Very Short Answer Type Questions:

Question (i)
Define sedimentation.
Answer:
Sedimentation is a process in which heavier particles of an insoluble solid settles down in liquid.

Question (ii)
What is evaporation ?
Answer:
The process of converting a liquid into its vapour form is called evaporation.

Question (iii)
For what purpose combine machine is used for ?
Answer:
Combine machine is used for both harvesting and threshing process.

6. Short Answer Type Questions:

Question (i)
Give difference between evaporation and condensation.
Answer:
The process of converting a liquid into its vapour form is called evaporation. The process by which vapours change to water is called condensation.

Question (ii)
Give difference between saturated solution and unsaturated solution.
Answer:
A saturated solution is that solution in which no more solute can be dissolved at a particular temperature. An unsaturated solution is that solution in which more solute can be dissolved at a particular temperature.

Question (iii)
Explain different types of threshing.
Answer:
Threshing can be done in following three ways:

1. Manual threshing : It is done by beating the stalks with sticks on the ground or beating against any hard object.
2. Threshing by Animals : Some animals like bullocks are allowed to trample the stalks.
3. Threshing by Machine. Threshers are generally used for this purpose.

7. Long Answer Type Questions:

Question (i)
Explain the following methods of separation.
(1) Threshing.
(2) Winnowing.
(3) Sieving.
Answer:
(1) Threshing. Threshing is separation of grains from chaff. It can be done using any one method out the three i.e. (a) manual (b) with the help of Animals and (c) using machines.

(2) Winnowing. Winnowing is a method to separate heavier and lighter components of a mixture by wind or by blowing air.
Winnowing is an agricultural method for separating grains from chaff. It is also used to remove hay and chaff or other pests from stored grains.

(3) Sieving. It is a method to separate larger substances from smaller substances using a sieve. It is very easy and cheap method of separation. Components of same sizes in a mixture cannot be separated. For example, you cannot separate chalk powder from flour.

Question (ii)
What is separation ? Why do we need to separate different components of a mixture ?
Answer:
Separation. Separation means process of moving something apart.
We need to sep.arate a mixture into its different components because of the following reasons :

1. To remove the useless or harmful components. For example, removing tea leaves after making tea.
2. To obtain the useful component. For getting wheat/rice grains after separating husk, dirt etc.
3. To remove impurities for getting a pure sample. For example – obtaining sugar crystals from sugarcane juice or salt from sea water.

PSEB 6th Class Science Guide Separation of Substances Important Questions and Answers

Multiple choice questions:

Question 1.
Salt is separated from sea water by :
(a) Evaporation
(b) Decantation
(c) Condensation
(c) Filtration.
Answer:
(a) Evaporation

Question 2.
Cottage cheese (Paneer) is made by adding to milk :
(a) lemon juice
(b) salt
(c) water
(d) tea leaves.
Answer:
(a) lemon juice

Question 3.
Fruit and vegetable juices are filtered to separate :
(a) Seeds
(b) Pulp
(c) Impurities
(d) seeds, pulp and impurities.
Answer:
(d) seeds, pulp and impurities

Question 4.
Filter paper is used in method :
(a) Sieving
(b) Filtration
(c) Condensation
(d) None.
Answer:
(b) Filtration

Question 5.
Sand and sawdust are separated by using method:
(a) Sieving
(b) Winnowing
(c) Hand picking
(d) All.
Answer:
(b) Winnowing

Question 6.
The purity of a substance is determined by:
(a) melting point
(b) colour
(c) source
(d) quantity.
Answer:
(a) melting point

Question 7.
The process in which liquid changes into vapours is:
(a) Sedimentation
(b) Filtration
(c) Evaporation
(d) Decantation.
Answer:
(c) Evaporation

Fill in the Blanks:

(a) Tea …………… are separated from liquid with a strainer.
Answer:
leaves

(b) We ……………… cotton to separate its seeds from the fibre.
Answer:
gin

(c) Butter is taken out by ……………… milk.
Answer:
churning

(d) Pieces of stone and husk are separated from wheat, rice or pulses by ………………
Answer:
hand picking

(e) ……………… are also used for threshing grains.
Answer:
machines

(f) Winnowing is used to separate ……………. and ……………. components of a mixture by blowing air.
Answer:
heavier, lighter

(g) Pebbles and stones are removed from sand by ………………
Answer:
sieving

(h) Larger quantities of salt can be dissolved in water on ………………
Answer:
heating

(i) A solution is prepared by …………….. a substance into a liquid.
Answer:
dissolving

(j) Water dissolves different substances in …………….. amounts.
Answer:
different

Write (T) against true and (F) against false statements :

(a) We cannot separate guavas and mangoes by hand picking.
Answer:
False

(b) We separate stones from rice to throw away them.
Answer:
True

(c) Grain seeds can be plucked like guavas.
Answer:
False

(d) Husk is used as a fodder for cattle.
Answer:
True

(e) Rice and pulses are washed before cooking.
Answer:
True

(f) For separating tea leaves, decantation method is used.
Answer:
False

(g) We cannot remove soil from water.
Answer:
False

(h) Paneer can be separated by using a strainer.
Answer:
True

(i) Sea water evaporates continuously.
Answer:
True

(j) Water drops cannot be condensed on cooling.
Answer:
False

Very Short Answer Type Questions

Question 1.
Give few examples of mixture.
Answer:
Air, sea water, soil, rock salt.

Question 2.
What is Churning ?
Answer:
Churning. It is process in which milk is stirred (rotated) to get the lighter particles of butter separated on the surface.

Question 3.
What is Decantation ?
Answer:
Decantation. It is process in which two immiscible liquids are separated by allowing them to stand for some time till they form two separate layers.

Question 4.
By which method heavy and light particles of a solid mixture are separated ?
Answer:
Winnowing.

Question 5.
Which materials are used as filters ?
Answer:
Porous materials such as thin muslin cloth and filter paper and nylon net.

Question 6.
Name some mixtures found in nature.
Answer:
Milk, Sea-water, Jaggery.

Question 7.
Give an example of a gaseous mixture.
Answer:
Air.

Question 8.
How will you separate a mixture of water and cooking oil ?
Answer:
By separating funnel.

Short Answer Type Questions

Question 1.
What is a mixture ? Give four examples of mixture.
Answer:
Mixture. A mixture is a substance which consists of two or more elements or compounds not chemically combined together in any ratio.
Examples : Air, sea water, soil, rock salt.

Question 2.
Write two properties of mixture.
Answer:

1. The constituents are not present in a fixed ratio.
2. It does not have a fixed melting and boiling point.
3. The various components of the mixture can be separated easily by physical methods.

Question 3.
How is salt separated from sea water ?
Answer:
Separation of Salt from Sea water. Water is collected in flat-square fields (lagoons) near the sea. It is allowed to stand for few days. Now water gets evaporated in the sun leaving behind crude crystals of salt. This crude salt is purified to get pure salt.

Question 4.
What is the criteria of separating the components of a mixture ?
Answer:
While choosing a method of separating different components of mixture, physical properties of components are considered.

Question 5.
Which methods are used to separate a mixture of sand, black gram (urad) and husk ?
Answer:
At first winnowing process is used to remove husk. Then sand is separated by using sieving process.

Question 6.
What is a solution ?
Answer:
Solution. A solution is a homogeneous mixture of a solid in a liquid. It can be prepared by dissolving a solid substance in a liquid.

Question 7.
What is saturated solution ?
Answer:
Saturated Solution. A solution which cannot dissolve more of the solute at the same temperature in it, is said to be saturated solution.

Long Answer Type Questions

Question 1.
What is filtration ? Write few activities where this method is being used.
Answer:
Filtration. The process of separating components of a mixture of an insoluble solid and a liquid is called filtration.
Activities in which filtration is used :

1. Fruits and vegetable juices to separate the seeds and solid particles of pulp.
2. Cottage cheese preparation to separate the whey.
3. Tea preparation to separate tea leaves.

Question 2.
What are different methods of separating mixtures ? Explain any two of them.
Answer:
There are many methods of separating mixtures :
They are :

1. Hand Picking
2. Threshing
3. Winnowing
4. Sieving
5. Sedimentation
6. Decantation
7. Filtration
8. Evaporation
9. Condensation.

1. Sedimentation.
The process of separating light and heavier components of a mixture by allowing it to stay undisturbed, is called sedimentation.
In this process, the mixture is dissolved in water. The heavier particles tend to settle down at the bottom and the lighter particles make the water muddy or just float on it. When this solution is allowed to stand for some time then a separate layer of heavier particles can be seen at the bottom.

This process is known as Sedimentation. The upper layer of impure water is removed to get a pure sample of substances e.g. rice, pulses, etc. are washed with water to get rid of dust and soil particles and husk components which are light and get removed by water easily.

2. Evaporation.
The process of conversion of water into its vapours is called evaporation. This process is continually taking place all around us. For vapour formation, heat is needed which is provided by sunlight.