Chapter 9 Methods of Separation in Everyday Life Class 6 Extra Questions and Answers Science Curiosity

Q1. What is a mixture?

Ans: A mixture is a combination of two or more substances mixed together in any proportion. In a mixture, no new substance is formed and each component retains its own properties. For example, grains mixed with stones form a mixture.

Q2. Why do we need to separate substances from mixtures?

Ans: We need to separate substances from mixtures to remove unwanted or harmful materials, to make food safe for eating, and to obtain useful substances. Separation also helps in improving the quality of materials used in daily life.

Q3. Give two reasons for separating substances before cooking.

Ans:Before cooking, substances are separated to:

1. Remove impurities like stones, dust, or husk.
2. Make food clean, hygienic, and fit for consumption.

Q4. Name any two impurities commonly found in grains.

Ans: Two common impurities found in grains are small stones and husk.

Q5. What challenge did Nani give Malli and Valli with grains?

Ans: Nani gave Malli and Valli a challenge to remove small stones from grains by hand while keeping their eyes closed, to help them understand the process of handpicking.

Q6. What is handpicking?

Ans: Handpicking is a method of separation in which unwanted solid substances are removed manually by hand from a mixture. It is commonly used when the impurities are visible and present in small quantities.

Q7. On what differences is handpicking based?

Ans: Handpicking is based on differences in size, colour, and shape between the components of a mixture.

Q8. When is handpicking considered a convenient method?

Ans: Handpicking is convenient when the unwanted particles are few in number, larger in size, and can be easily seen and picked by hand.

Q9. Give two examples where handpicking is used in daily life.

Ans: Removing stones from rice or pulses and separating chillies or whole spices from cooked food.

Q10. Why cannot handpicking be used when impurities are present in large quantities?

Ans: Handpicking cannot be used when impurities are present in large quantities because it becomes very time-consuming, tiring, and inefficient.

Q11. What is threshing?

Ans: Threshing is the process of separating grains from harvested stalks by beating them. It helps farmers collect grains after harvesting crops.

Q12. Why are harvested stalks beaten by farmers?

Ans: Farmers beat harvested stalks to loosen and separate the grains that are attached to the stalks.

Q13. What gets separated during threshing?

Ans: During threshing, grains are separated from the stalks.

Q14. Name the traditional activity used to separate grains from stalks.

Ans: The traditional activity used is manual threshing, where stalks are beaten on a wooden log.

Q15. Which machines are now used instead of manual threshing?

Ans: Nowadays, machines called threshers are used to perform threshing efficiently.

Q16. What is winnowing?

Ans: Winnowing is a method of separation in which lighter components of a mixture are separated from heavier components using wind or blowing air.

Q17. Which components are separated by winnowing?

Ans: Winnowing separates lighter husk from heavier grains.

Q18. Which component gets blown away during winnowing?

Ans: The lighter husk gets blown away by wind during winnowing.

Q19. What tool is traditionally used for winnowing?

Ans: A soop (bamboo tray) is traditionally used for winnowing.

Q20. Why does winnowing not work in a closed room?

Ans: Winnowing does not work in a closed room because there is no moving air or wind to blow away the lighter particles.

Q21. How do threshers help farmers?

Ans: Threshers help farmers by performing both threshing and winnowing together, reducing manual labour and saving time.

Q22. Which two processes are performed together by threshers?

Ans: Threshing and winnowing.

Q23. What is sieving?

Ans: Sieving is a method of separation used to separate solid particles of different sizes using a sieve.

Q24. Which type of mixtures are separated by sieving?

Ans: Solid–solid mixtures where the components differ in size.

Q25. What happens to bigger particles during sieving?

Ans: Bigger particles remain on the sieve and do not pass through the holes.

Q26. What happens to finer particles during sieving?

Ans: Finer particles pass through the holes of the sieve.

Q27. Why must sieve holes be of proper size?

Ans: The holes must be of proper size so that only fine particles pass through while larger particles are retained.

Q28. Give two examples where sieving is used.

Ans: Separating bran from wheat flour and Separating stones from sand at construction sites.

Q29. Why is sieving used at construction sites?

Ans: Sieving is used to separate pebbles and stones from sand to obtain fine sand for construction.

Q30. From where is common salt obtained?

Ans: Common salt is obtained from seawater.

Q31. How is salt obtained from seawater?

Ans: Seawater is kept in shallow pits and exposed to sunlight. The water evaporates, leaving behind salt.

Q32. What happens to water kept in shallow pits under sunlight?

Ans: The water gradually evaporates due to heat from the sun.

Q33. What remains after evaporation of seawater?

Ans: Solid salt mixture remains after evaporation.

Q34. What is evaporation?

Ans: Evaporation is the process in which a liquid changes into vapour on heating or exposure to air.

Q35. Name one salty water body in India.

Ans: Sambhar Lake in Rajasthan.

Q36. What forms when salt is dissolved in water?

Ans: A salt solution is formed.

Q37. What is observed on black paper after salt solution dries?

Ans: White salt patches are observed on the paper.

Q38. Why do white patches appear on clothes in summer?

Ans: Sweat evaporates and the dissolved salt remains on the clothes as white patches.

Q39. Where does the water go during drying?

Ans: Water evaporates into the air as water vapour.

Q40. What remains after water evaporates?

Ans: Salt remains behind.

Q41. What happens when salt solution is heated in a china dish?

Ans: Water boils away and solid salt remains in the china dish.

Q42. What is left behind after boiling?

Ans: Salt is left behind.

Q43. Can both salt and water be obtained back? Which process helps?

Ans: Yes, both can be obtained back using evaporation followed by condensation.

Q44. What safety precaution should be followed while heating?

Ans: Care should be taken while heating the china dish to avoid burns.

Q45. What is sedimentation?

Ans: Sedimentation is the process in which heavier insoluble particles settle at the bottom of a liquid.

Q46. What is decantation?

Ans: Decantation is the process of carefully pouring the clear liquid after sedimentation.

Q47. Why is decantation not a perfect method?

Ans: Because some fine particles may still remain mixed in the liquid.

Q48. Give two household examples of decantation.

Ans: Washing rice and washing pulses

Q49. Which type of particles settle at the bottom?

Ans: Heavier and insoluble particles.

Q50. How can oil be separated from water?

Ans: Oil can be separated from water by decantation because oil floats on water.

Q51. What is filtration?

Ans: Filtration is a method of separation used to separate insoluble solid particles from a liquid by passing the mixture through a filter. The filter allows the liquid to pass through while stopping the solid particles.

Q52. What is residue?

Ans: The solid particles that remain on the filter paper after filtration are called residue. For example, mud left on filter paper during filtration of muddy water.

Q53. What is filtrate?

Ans: The clear liquid that passes through the filter and is collected in another container is called filtrate.

Q54. Why is cloth able to act as a filter?

Ans: Cloth has very small holes or pores between its threads. These pores allow water to pass through while stopping larger insoluble particles.

Q55. Why is filter paper better than cloth?

Ans: Filter paper has much finer pores than cloth, so it can trap very small particles and gives clearer filtrate.

Q56. Name any three materials that can act as filters.

Ans: Cloth, cotton, sand, charcoal, and filter paper can act as filters.

Q57. What happens to mud during filtration?

Ans: Mud particles do not pass through the filter paper and remain on it as residue.

Q58. Where is the clear water collected during filtration?

Ans: The clear water is collected in the conical flask or container placed below the filter.

Q59. What material were early tea bags made of?

Ans: Early tea bags were made of soft cloth like silk.

Q60. Why was silk first used for tea bags?

Ans: Silk was strong, could hold tea leaves properly, and allowed hot water to pass through without tearing.

Q61. Which material is used for tea bags today?

Ans: Today, filter paper is used to make tea bags.

Q62. What is churning?

Ans: Churning is a method of separation used to separate butter from curd by rotating or stirring it continuously.

Q63. Which two products are obtained during churning?

Ans: Butter and buttermilk are obtained during churning.

Q64. Why does butter float on top during churning?

Ans: Butter floats because it is lighter than buttermilk.

Q65. Name one electric appliance used for churning.

Ans: Mixer, grinder, or electric churner.

Q66. Which separation method is used to obtain butter from curd?

Ans: The method used is churning.

Q67. What are magnetic substances?

Ans: Substances that get attracted towards a magnet are called magnetic substances.

Q68. Give one example of a magnetic substance.

Ans: Iron.

Q69. What is magnetic separation?

Ans: Magnetic separation is the method of separating magnetic substances from non-magnetic substances using a magnet.

Q70. How were iron nails separated from sawdust?

Ans: A magnet was moved through the sawdust, and the iron nails got attracted to it.

Q71. Why do recyclers use magnets?

Ans: Recyclers use magnets to separate iron articles from waste so that they can be recycled and reused.

Q72. Where are cranes fitted with magnets used?

Ans: They are used in industries and scrap yards to separate iron from waste materials.

Q73. What unwanted items were caught in the fishing net?

Ans: Plastic bags, broken bottles, food wrappers, and straws were caught along with fish.

Q74. Why is plastic harmful to aquatic life?

Ans: Plastic can injure aquatic animals, block their breathing, and sometimes cause death when swallowed.

Q75. Write one line on stopping plastic pollution.

Ans: Plastic pollution should be stopped at its source to protect rivers, oceans, and aquatic life.

Q76. Which method is used to separate stones from pulses?

Ans: Handpicking is used because stones are larger and easily visible.

Q77. Which method is used to separate butter from curd?

Ans: Churning is used to separate butter.

Q78. Which method separates husk from grains?

Ans: Winnowing separates lighter husk from heavier grains.

Q79. Which method separates bran from flour?

Ans: Sieving separates bran from flour.

Q80. Which method separates tea leaves from tea?

Ans: Filtration using a strainer.

Q81. Which method separates chalk powder from water?

Ans: Filtration.

Q82. Which method separates iron from waste?

Ans: Magnetic separation.

Q83. Which method separates salt from salt solution?

Ans: Evaporation.

Q84. Why is evaporation useful in separation?

Ans: Evaporation helps separate a dissolved solid from a liquid by converting the liquid into vapour.

Q85. Why does sedimentation occur?

Ans: Sedimentation occurs because heavier insoluble particles settle down due to gravity.

Q86. Why is pore size important in filtration?

Ans: The pore size determines which particles can pass through and which will be retained.

Q87. How are nasal hairs related to filtration?

Ans: Nasal hairs act as filters by trapping dust particles from air.

Q88. What role do masks play?

Ans: Masks filter dust, germs, and harmful particles from air and protect us from diseases.

Q89. Why are several methods needed for mixtures with many components?

Ans: Different components have different properties, so multiple methods are needed for complete separation.

Q90. How to Separate the Following Mixtures

Ans:

1. Separating small stones from pulses — Handpicking
2. Churning curd to obtain butter — Churning
3. Taking out green chillies from cooked dalia or poha — Handpicking
4. Taking out seeds from watermelon — Handpicking
5. Sorting piles of sawdust and iron nails from a mixed heap — Magnetic separation
6. Picking marigold flowers from a heap of other flowers — Handpicking
7. Separating pebbles from sand — Sieving
8. Separating coconut pieces from rice flour — Sieving
9. Separating oil from water — Decantation
10. Separating salt from salt solution — Evaporation