TS Board Telangana SCERT Class 6 Science Solutions 7th Lesson Separation of Substances Textbook Questions and Answers.
Separation of Substances – TS 6th Class Science 7th Lesson Questions and Answers Telangana
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Is It possible to separate sugar mixed with wheat flour ? If yes, how will you do it ? If powdered sugar is mixed with wheat flour, how do you separate them? (Conceptual Understanding) 8M
- Yes, it is possible to separate sugar mixed with wheat flour.
- They can be separated by sieving, using a sieve with a proper pore – size. The flour particles are very fine and pass through the holes of the sieve. The sugar pa rticles being large are left on the sieve.
- The mixture containing powdered sugar and wheat flour is dissolved in water. Sugar only dissolves. Flour does not dissolve. They are separated by filtration, using a filter paper. Flour remains in the filter paper. It is dried. We get the flour.
The sugar solution is slowly evaporated. Water evaporates. Sugar is left over in the dish. Thus, flour and sugar are separated.
Why is hand picking necessary after winnowing ? (Conceptual Understanding) 4M
- Some undesirable substances such as pieces of stones remain in rice or dal. After winnowing also they can be separated by hand picking.
- This is possible because the particles of the undesirable substances are different from the food grains in colour, shape and size and easily identified with eye.
- This method is convenient when the undesirable components are present in small quantities.
Srikar accidentally mixed mustard seeds with rice and salt. How can he separate them? (Experimentation andfield Investigation) 8 M
The separation is done in 3 steps:
- Mustard seeds are separated by sieving.
- The mixture containing rice and salt is shaken with water, salt dissolves, leaving rice. They are separated by filtration using a filter paper. Rice collects on the filter paper.
- Now the salt solution is carefully evaporated by crystallization process. Then water escapes, leaving the salt in the dish. Thus mustard seeds, rice and salt are separated from their mixture.
Which separation process is used when one component is in a mixture: (Conceptual Understanding) 8 M
(a) Heavier then the other?
(b) Bigger than the other ?
(c) Different shape and colour from the other ?
(d) One is soluble in water and the other is not ?
Filtration and then crystallization.
(e) One floats and the other sinks in water ?
Decantation using a sieve. The floating substance collects in the sieve. The heavier substance remains in the container.
Visit a nearby dairy and report about the processes used to separate cream from milk. (Information Skills and Project) 2M
- Certain amount of milk is allowed into a container.
- The container’s plug (spigot) is closed tightly at the bottom of container.
- It is undisturbed for 24 hours.
- Then plug is opened. It is observed that the skimmed milk (butter less milk) comes out, leaving the creamline floating at the top.
- Once the milk layer becomes thik at the end, it is separated and collected from the container.
Divya suggested some methods to separate mixtures given below. Are they correct ? Find whether they are possible or not. Give reasons (Conceptual Understanding) 8M
(a) Pure water can be obtained from sea water by the process of filtration.
Reason : Sea water contains many dissolved salts. These salts cannot be separated from water by filtration. •
(b) Cheese is removed from curdled milk by the process of decantation.
Reason : When milk curdles, it separates into solid and liquid parts. The solid part is separated from the liquid part, by decantation.
(c) Separation of sugar from tea can be done by filtration.
Reason : Sugar dissolves in tea. So it cannot be separated by filtration.
Collect information from your parents regarding various methods used by us to clean food grains at home and prepare a chart to show them. (Students should collect information and prepare a chart). (Experimentation and field investigation) 4M
|Process of separation
|1) Stones from grain
|2) Husk from wheat flour
|3) Fine particles of sand from mustard seeds
We observe that Kerosene rises up in the wick of a lantern. Take a wick and put a spot of ink at one of its ends. Then dip the wick in Kerosene just as you had dipped the chalk in water in the chromatography activity. Will your experiment be successful in separating the colour ink spot. Try it. (Experimentation andfield investigation) 2M
Different colour bands appear on the wick, after sometime.
Match the following and write sentences in your note book. (Conceptual Understanding / Asking questions and making hypothesis) 4M
|A) A substance obtained by mixing two or more pure substances
|B) A clear liquid obtained after filtration
|C) A solid changing directly into vapour
|D) A method for removing the husk from grain
|E) Removing insoluble impurities from muddy water by allowing it to settle
Draw a picture of article used for separation of mixture in your house. (Communication through drawing and model making) 4M
Kiran observed his father separating husk and grains by winnowing method in the field and appreciated how wind flow helped in separation. On evaporation salt is formed from sea water. Isn’t it ? How would you appreciate (Appreciation and Aesthetic sense and values) 8 M
(1) Kiran’s father stood on a high platform and allowed the mixture of grain and husk to drop slowly from the flat pan. The wind carried away the husk forward. The grains fell vertically downward. Thus a separate heap of grain is formed.
(2) Sea water is allowed to stand in shallow pits. Water gets heated by sunlight and slowly turns into water vapour and escapes out. (Process is called evaporation). In a few days, the water evaporates completely leaving behind solid salts (a mixture of salts). Common salt is thus obtained from this mixture of salts by further purification.
TS 6th Class Science 7th Lesson Notes – Separation of Substances
- We separate the components of mixtures for different purposes in our daily life.
- Items like tea, lemon juice, soil etc., contain more than one substance. So they are called, mixtures.
- There are natural mixtures, as well as man-made mixtures.
- We make use of several properties of the materials for separating the desired items from the mixture.
- An Example:
- When a mixture of water, sand and mud is allowed to remain undisturbed for sometime, sand along with the mud settles down at the bottom of the container. These are called, sediments. This process of separation of sand and mud from water is called sedimentation.
- Mixture : Combination of more than one substance is called a mixture.
- Separation : We follow different methods to separate substances from a mixture. :
- Hand picking : The substances which are carefully chosen and separated by hand from the mixture is called hand picking.
- Winnowing : The method of separating the heavier material from the lighter material. Separating the substances in the mixture by wind or by blowing air is called winnowing.
- Sedimentation : The solid material that settles at the bottom of a liquid is called a ‘sediment, and the process is called sedimentation.
- Decantation : The process of separation of clear upper liquid from the sediment is called decantation.
- Sieving : It is a method used to separate fine particles from large particles in a mixture using sieve.
- Filtration : It is a process of filtering a substance.
- Crystallization : Crystallization is a process used to separate dissolved solid substances from a liquid.
- Distillation : The process used to remove impurities from water is called distillation.
- Sublimation : The process in which a substance changes directly from solid to gaseous form and vice-versa is called sublimation.
- Chromatography : The process of separating the components of mixture, by passing it through a material.