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DAV Class- 6 Science Separation of Substances Question and Answer
Something To Know
A. Fill in the blanks.
1. Housewives sometimes use the method of handpicking to remove unwanted substances from eatables like rice and pulses.
2. Common salt is prepared on a large scale through the process of evaporation.
3. Separation of tea leaves from tea is done by a process called filtration.
4. The process of loading can be used to increase the rate of sedimentation of the suspended particles in a solid-liquid mixture.
5. The method, used to separate the fine particles, suspended in a liquid, by rotating the mixture at high speed, is known as centrifugation.
B. Match the following:
| Column 1 | Column 2 (Answer) |
| 1. Wind- | winnowing |
| 2. Chalk powder and water – | sedimentation |
| 3. Oil and water – | separating funnel |
| 4. separating peas from cooked pulao – | hand picking |
| 5. Muslin cloth – | filtration |
| 6. Camphor and salt – | sublimation |
C. Tick the correct option.
1. Which of the following is an example of a heterogeneous mixture?
Answer 1: an aerated drink
2. Which of the following is not an example of a pure substance?
Answer 2: air
3. The process of loading helps to-
Answer 3: speed up the rate of sedimentation
4. Transferring the clear liquid, into another container, leaving behind the residue, is called-
Answer 4: decantation
5. A substance, that sublime easily, is –
Answer 5: naphthalene
D. Answer the following questions in brief.
1. Name any three methods used for separating a solid-solid mixture.
Answer 1: (1) Hand picking (2) winnowing (3) Magnetic separation
2. What is winnowing? Give an example of a mixture whose components can be separated by this method.
Answer 2: The process of separation of lighter particles from heavier ones by wind.
Example: Separation of husk from wheat
3. Some iron pins get scattered on the carpet when you are expecting guests. How can one collect all the pins in the shortest possible time?
Answer 3: By the process of Magnetic separation.
4. Name any three substances which sublime on heating.
Answer 4: (1) camphor (2) iodine (3) naphthalene
5. What is crystallisation? Name any three substances which can be purified using this technique.
Answer 5: Crystallisation is the process that separates a pure solid in the form of its crystals, from a saturated solution.
Salt, alum and blue vitriol are purified using crystallisation.
E. Answer the following questions.
1. Differentiate between a pure substance and a mixture. Give two examples of each.
Answer 1: Pure Substance – It is made up of only one type of substance.
Example: Gold, Pure Water
Mixture – A mixture is made up of two or more substances are mixed together in any proportion.
Example: Sand, Air
2. State the difference between heterogeneous and homogeneous mixtures. Give two examples of each type.
Answer 2: Heterogeneous mixture – A heterogeneous mixture is one in which the components are not equally distributed and do not have the same composition throughout the mixture.
Example: Mixtures of sand in water, iron nails in sulphur powder.
Homogeneous mixture- A homogeneous mixture has the same composition throughout, meaning that its components are evenly distributed.
Example: A solution of salt or sugar in water, soft drinks.
3. Can a mixture of iodine and camphor be separated by the sublimation method? Give reason for your answer.
Answer 3: No, we cannot use the sublimation method for a mixture of Iodine and camphor. As we know that sublimation is the process in which solid is directly converted into gas.
As the camphor and iodine are sublime compounds. So, upon heating, both go to a gaseous state. And then in a gas form, we can’t identify which one of them is iodine or camphor.
4. Why does the size of naphthalene balls, put in open, keep on reducing with time?
Answer 4: Sublimation causes the size of Naphthalene balls in open containers to shrink over time. Because naphthalene is exposed to the elements, it absorbs heat from the environment, and this heat sublimes the naphthalene.
5. After a dust storm, how does rain help in making air clear?
Answer 5: Rain droplets load the dust particles and make them heavier, so dust particles settled down on land and air becomes clear.
6. Sawdust, mixed in water, cannot be separated by the sedimentation method. Why?
Answer 6: As the sawdust is lighter so it floats. Sedimentation, on the other hand, uses the substance to settle down in the water. When the mixture of sawdust and water is left undisturbed, the sawdust will not settle down in the water. As a result, the sedimentation process cannot separate sawdust.
7. The filtration method cannot be used to separate sugar and salt mixed in water. Why?
Answer 7: Filtration is a method that is used to separate insoluble solids from a liquid. Since salt and sugar both dissolve in water, filtration cannot be used to separate salt and sugar.
8. Describe the method of centrifugation using an appropriate example.
Answer 8: It is a technique for separating small particles floating in a liquid by rapidly rotating the mixture. A machine called a centrifuge is used to perform centrifugation. The heavier particles sink to the bottom of the container, while the lighter particles rise to the top. Centrifugation is used to separate cream from milk by churning it.
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