CLASS– VI : SEPARATIONS OF SUBSTANCE

CLASS– VI ASSIGNMENT SEPARATIONS OF SUBSTANCE
Q.1 What is separation?

Q.2 Why the separation of substances is necessary?

Q.3 What is the basis of separation of components of mixture?

Q.4 When do we use hand picking as the method of separation?

Q.5 What is threshing? How is it done?

Q.6 Define winnowing? What is the principle of using winnowing as method of separation?

Q.7 Where do we find sieving as the method of separation?

Q.8 You are given a mixture of sand, salt and iron filling. Suggest some methods for separating all the components of this mixture?

Q.9 Define filtration? Give 3 examples where filtration method is used.

Q.10 What is evaporation? Where do we use this method at home?

Q.11 What method is used to separate salt from sea water and how?

Q.12 In which cases handpicking is enough as a method of separation?

Q.13 One method of separation is not enough. Comment.

Q.14 Differentiate between a pure substance and a mixture.

Q.15 Is the separation of two immiscible liquids using separating funnel same as decantation?

Q.16 What do you use to remove discarded tea leaves from tea?

Q.17 What impurities are present when you buy wheat, rice or pulses from the market?

Q.18 What is the process called when stem of plants (stalks) are beaten to separate grains?

Q.19 What process is used to separate light solid particles from heavier solid particles?

Q.20 What will settle down when mud and rice are added to water?

Q.21 What is the process called when strainer or filter funnel is used?

Q.22 What is a solution called which contains the maximum amount of dissolved solute?

Q.23 How do you separate a light liquid from a heavier liquid?

6th Science : Separation of Substances Hots question

SEPARATION OF SUBSTANCES
1. You are given a mixture of sand and water. How do you separate them?
2. Your are given a mixture of water and oil. Using an empty cool drink bottle, How do you separate them?
3. Your are asked to dissolve sugar in water. You kept on adding sugar to water till some of the sugar is not at all dissolving by stirring with the spoon. How can you dissolve the left out sugar?
4. After the games period, you had come back to your class room and under a fan.
5. Your body becomes so cool and you feel so comfortable. Why?
6. If you keep Ice pieces in glass tumbler, you observe lot water droplets on the Surface of the tumbler. Why?
7. River water is clear where as sea water is not even though, both contains mud and sand. Why?

CBSE 6th Science : Separation of Substances solution

Q. What is solution?

Ans: A solution is a mixture of two or more substance  so that properties are the same throughout . The substance in large quantity is called solvent and The substance in small quantity is called solute.

Q. What is saturated solution?

Ans: if solvent cannot dissolve more solute at room temperature is called saturated solution. A solution is said to be unsaturated as long as more solute can be dissolved.

Q6. State the method used for separating following mixtures:

a) Separating iron from sulphur              magnetic separation

b) Separating oil from water                   decantation

c) Chalk from water                               filtration

d) Bran from flour                                  sieving

e) Pulses from rice                                hand picking

Q. How fat separated from milk?

Ans: Centrifugation or churning method. The method separation involving high speed is called churning using centrifuge machine.

Q. Name process of separating husk from grain?                                                           

Ans: winnowing

Q. How can you turn water vapour into water                                                       

Ans: On cooling called condensation.

Q. what is condition in which no more solute can dissolve in the solvent?                        

Ans: Saturated Solution

Q. What is the left over material known as?                                                         

Ans : Residue

Q. By which process you get flour from husk?                                                   

Ans: Sieving

Q. How do you clean grain at home ?                                                                 

Ans: Hand picking and Sieving

Q. name the part of plant in which grains are embedded ?                                

Ans: Cob

Q. What is the method in which heavier particle allow to settle down?            

 Ans: sedimentation

Q. How are stone and pebble are separated on construction site?                 

Ans : by using sieve called Sieving

Q. How do you carry out churning?                                                                    

Ans: By rotating solution rapidly.

Q. How Chaff or husk is separated from grain after harvesting?              

Ans: It is separated by threshing using thresher.

Q. Explain the method of obtaining common salt from sea water.

Ans. Sea water is collected in shallow pits dug on the sea shore. The heat of sun evaporates water. When enough water has evaporated the solution becomes concentrated, then the salt begins to crystallize.

Q. what is thresher and why it is called an efficient machine  ?

Ans: thresher is a machine that separate husk from grain. It can remove husk ,dusk and produce neat and clean food grain so it is called an efficient machine  .

Q.Fill up the blanks :

(1) The method of separating seeds of paddy from its stalks is called ................... .
(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 ................... .
(3) Salt is obtained from sea water by the process of ................... . 
(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 ....................

Ans. (1) The method of separating seeds of paddy from its stalks is called threshing.

(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 sea water 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 decantation.

CBSE 6th Science : Separation of Substances merit gain questions

Q. What is supernatant liquid ?

Ans: A clear liquid that collected by decantation is called supernatant liquid.

Q. Define loading.

Ans : The process of increasing the rate of sedimentation ion by adding potash alum (fitkiri)  to it is called loading.

Sometimes very fine solid particles do not sink to the bottom during sedimentation.

By adding potash alum impurities became heavier and settle down .eg. muddy water, cleaning of river water .

Q. What is Filtration?

Ans: Filtration is a separation technique that is used to separate a solid that has not dissolved in a liquid.

In this process mixture of the solid and liquid is allow to pass  through the filter paper.

The clear liquid separated in the container is called the filtrate. The solid that remains in the filter paper is called the residue.

Q. Why filtration is preferred over decantation?

Ans:  Sometimes in decantation the liquid is not completely separated from an insoluble liquid then we  apply  the method of decantation.

Q. Why do we employ the method of loading sometimes after sedimentation and  decantation?

Ans. Loading helps sedimentation. Sometimes very fine solid particles do not sink to the bottom, they remain suspended in water so these fine particles can be separated from loading.

Q.  What is evaporation?

Ans: The process of changing water into water vapor

Q.  What do you mean by method of evaporation?

Q. what is condensation?

Ans: Conversion of water vapour into liquid on cooling is called condensation.

Ans.The process of removing water or moisture from a mixture either by heating or by direct sunlight is called evaporation, e.g., salt from sea water is obtained by this method.

Q. How can you separate a mixture of salt & sand?

Ans. we add the given mixture in water and left undisturbed for some time.  sand particles settle down at bottom and  salt get dissolved in water . we apply the method of filtration or decantation to obtain salt water solution.  After that s evaporate salt solution and we obtain salt.

Q. What is magnetic separation?

Ans. The process of separating a magnetic substance from a non-magnetic substance, by using a magnet is called magnetic separation. For example, impurities of iron.  

Q. How will you separate a mixture of iron fillings and sulphur ?

Ans:  A mixture of iron fillings and sulphur can be separated by magnetic separation. We take a magnet and move it through the mixture till the whole of iron fillings are attracted by the magnet. Remove the iron fillings from the magnet and keep them separately. Sulphur powder is left beind on the sheet of paper.

Q. How will you separate a mixture of iron filings, sand and common salt ?

Ans We take a magnet and move it through the mixture till the whole of iron fillings are attracted by the magnet . Now dissolve the mixture in 100 ml of water. Filter the mixture. The sand is left on the filter paper, and the clear common salt solution collects as a filtrate.  Now,  we heat salt solution. In a few minutes, water evaporates, leaving behind dry common salt.

6th Science : Cleaning of food or Separation of Substances solved question

Q. What is substance?

Ans: A kind of matter that cannot be separated by physical methods.

Q. What is pure substance?

Ans: Clean and diseases free substance are called pure substance.eg. elements.

Q. what is matter?

Ans: Everything around us having mass and volume is called matter. it is of three types element compound and mixture.

Q. What is compound?

Ans: Ans: The substance containing two or more types of substance mixed together in fix ratio is called compound.eg salt, sugar and water

Q. What is mixture?

Ans: The substance containing two or more types of substance mixed together in any ratio is called mixture.eg. air , food  grain, milk, sea water. A mixture can be separated by physical methods.

Q. Give two properties of mixtures.

Ans. (i) The ratio of their constituents is not fixed.
(ii) Mixtures do not have definite melting point or boiling point.

Q. Why we need to separate mixture?

Ans:  The following are the reasons for the separation:

(i) to remove the undesirable constituents from mixture. (ii) To obtain desirable substances from mixture.  (iii) To obtain highly pure substance.

Q. What is Chaff or husk?

Ans: the debris arising from agriculture processing of food grain like maize, rice wheat is called chaff.

Q. Differentiate between hand picking & winnowing.

Ans. Hand picking: the process of cleaning mixture by picking out with hand.

It is used when the constituents of the mixture are big in size & visibly differently .For example: separating stones from rice.

Winnowing: The process of cleaning mixture like husk from grain with the help of wind which blow lighter husk.

It is used when one of the constituents is lighter and  the other is heavier, For example:  shaff from grain.

Q. Define sieving

Ans: The process of separating fine lighter particles from larger particles using sieve. Eg husk, gravel, dust ,tea leaves etc .

Size of the holes of sieve or mash depends on the size of particles separated.

if the solid mixture is stirred or shaken on a mesh. Particles smaller than the holes of the mesh fall & the bigger ones remain on the mesh.

Q. what is sedimentation and decantation?

Ans: The process of separating heavier insoluble solid particles mixed in liquid. For separating we left mixture u disturbed for some time.  The heavier particles settle down at bottom is called sediment.

The method of collecting clear liquid from sediment is called decantation.