Separation of Substances Class 6 Science

Important question and answers of Separation of Substances

CBSE Class 6 Science

1.The dust particles in the water can be helped to se ttle down faster by using
Ans.Alum

2.The process by which the unwanted solid particles a re removed from the liquid is called
Ans.Filtration



3.Common salt is obtained from sea water by
Ans.Evaporation

4.The pure substance have fixed
Ans.Melting point

5.A solution of salt is a
Ans.Homogeneous Solution

6.The properties used to separate two solids from a m ixture by winnowing is
Ans.Difference in weight

7.Most of the substance that see around us are
Ans.Mixtures

8.The method of separation used to separate stone fro m rice is
Ans.Hand picking

9.The separation of grains from husk in done by the p rocess of
Ans.Winnowing

10.Chalk powder suspension in water can be separated b y
Ans.Filtration

B.Fill in the Blanks
1.Fills in the blanks.
a. Pure liquid is obtained from its solution by the pr ocess of -------------.
b. Rice is separated from common salt by ------------- ---.
c. Tea leaves from tea are separated by -------------- -.
d. ------------------ help in the clay particles in su spension to settle down.
e. Mustard oil is separated from water by ------------ ---.
(a) distillation (b) filtration (c) filtration (d) sedimentation (e) decantation.

2.Fill in the blank with suitable word.
a. Machine that performs the function of harvesting as well as threshing is called - -----------------.
b. Sieving is possible only, when the particles of a m ixture are of ------------ size.
c. The process of settling of heavy material at the bo ttom is called--------------.
d. The clean liquid obtained after filtration is calle d ----------------.
e. --------------------- is used to separate impuritie s from suspension.
(a) combine harvester (b) different (c) Sedimentati on (d) filtrate (e) loading.

3.Short Question and Answers
1.Define
a. Centrifugation
b. Winnowing
Ans.(a) The process of separation in which constituent particles are separated on the basis of difference in their density. When mixture rotate d very fast, the lighter particles moves up. Example cream from milk.

(b) Winnowing is the separation method in which lig hter and heavier particles are separated by wind. Example: husk from grains.

2. How will you separate husk or dirt particles from p ulses before cooking?

Ans.The husk and dirt from the pulse is separated by wa shing the pulse properly in which dirt moves out with water. The husk can be separate d by winnowing also. Pulses are insoluble so it does not harm the nutrient value of pulse.

3. Explain sieving. Is it good practice to sieve flour before consuming it? Why?

Ans.The separation method in which mixture is separated by difference in size particles using a sieve. The smaller particles moves down and larger particle remain in sieve. No, sieving of flour is not a good practice because it remove the bran that contain protein and starch.

4. Name the method that is used to separate following mixture.
a. Cream from milk.
b. Chalk and water
c. Mud and water
d. Saw dust and water.
Ans.Following methods are used to separate the mixture
a. Churning or centrifugation
b. Filtration
c. Sedimentation and decantation.
d. Filtration.
5. How clean water is obtained from muddy water?
Ans.Clean water can be obtained from muddy water by eva poration and condensation process. In this process, muddy water is heated to its boiling point to form vapour. The vapour is collected and cooled to get pure water.

6. What is threshing? How it is done?

Ans. It is a separation method in which seed is separat ed from stalk of the plant such as paddy and wheat. In this method, stalk is beaten on hard surface or domestic animals are moved on sprayed stalk.

7. Why the separation of substance is necessary?

Ans.Separation of substance is necessary to a. Remove unwanted substance.
b. Selected the required substance.
c. To make food clean and palatable.

8. You are given a mixture of sand, salt and iron fill ing. How will you separate all the components?
Ans.Mixture of sand, salt and iron filling is separated as follows:
a. A strong magnet is moved thought the mixture to att ract the iron filling.
b. Remaining mixture of sand and sugar is dissolved in water
c. Filtration of solution separates the sand from the sugar.
d. Sugar solution is evaporated to obtain sugar.

9.What impurities are present when you buy rice, whea t and pulses from the market?

Ans.Impurities present in rice are small stone and husk , in wheat soil particles and in pulses stone particles, colouring materials and inf erior quality other pulses are mixed.

10. When do you use handpicking as a method of separati on of mixture?

Ans.If mixture comprises solids of different colour, sh ape and size, it can be separated by handpicking. The amount of impurities present in sm all and material to be cleaned is also less in quantity.

11. Mention different process involved in obtaining pur e salt from sea water.

Ans.Different process involve in obtaining pure salt fr om sea water is as follows:
a. Evaporation of sea water in shallow pit.
b. Collecting the remaining residues after evaporation .
c. Removing the other salts by filtration.
d. Crystallization of salt by dissolving in small quan tity of water.