Class 6 Science Chapter 9 Extra Questions and Answers – Methods of Separation in Everyday Life
Class 6 Science Chapter 9 Extra Questions and Answers for “Methods of Separation in Everyday Life” (based on NCERT textbook Curiosity).
EXTRA IMPORTANT QUESTIONS WITH ANSWERS – Chapter 9 – Methods of Separation in Everyday Life
This includes All types of Questions normally asked in school exams, tests, and NCERT exercises.
1. Why do we need to separate substances from a mixture?
Answer:
We need to separate substances for the following reasons:
• To remove harmful or unwanted substances
• To obtain two or more useful components
• To improve the quality of a substance
• To make the substance safe for eating or using
• To separate pure substances from mixtures
2. What is a mixture? Give two examples from the chapter.
Answer:
A mixture is a combination of two or more substances that are physically mixed but not chemically combined.
Examples:
• Grains mixed with stones
• Wheat grains mixed with husk
3. State the principle behind handpicking.
Answer:
Handpicking works on differences in:
• Size
• Colour
• Shape
• And when the unwanted component is present in very small quantity
4. Why is handpicking not suitable for large-scale separation?
Answer:
Handpicking is slow, time-consuming, and practical only when the impurities are very few. Large heaps of grains cannot be separated manually.
5. Explain threshing with an example.
Answer:
Threshing is the process of beating harvested crop stalks to separate grains from the stalk.
Example: Farmers beat wheat stalks on a log of wood to separate wheat grains.
6. Which separation method is used to remove husk from grains? Why?
Answer:
Winnowing is used because husk is light and gets blown away by wind, while grains being heavier fall straight down.
7. What is winnowing? Give one example from your home.
Answer:
Winnowing is separating lighter and heavier particles by wind or blowing air.
Example: Separating tea dust from large dried tea leaves using a fan or breeze.
8. Why is winnowing not possible in a closed room?
Answer:
Because wind or air movement is needed to blow away the lighter husk. In a closed room, there is insufficient airflow.
9. Define sieving.
Answer:
Sieving is separating solid-solid mixtures based on particle size using a sieve with holes. Smaller particles pass through, larger particles remain on the sieve.
10. Give two places where sieving is used.
Answer:
• In kitchens to remove bran from flour
• At construction sites to remove stones from sand
11. What is evaporation? Mention a use from the chapter.
Answer:
Evaporation is the process in which liquid converts into vapour.
Use: Obtaining salt from seawater by drying it in shallow pits.
12. Why does a white patch appear on dark clothes in summer?
Answer:
Sweat contains dissolved salts. When sweat evaporates, salt remains on the cloth, forming a white patch.
13. What is sedimentation? Give one example.
Answer:
Sedimentation is the settling down of heavier insoluble substances at the bottom of a liquid.
Example: Mud settling at the bottom of muddy water.
14. What is decantation?
Answer:
Decantation is the process of gently pouring clear water into another container after sedimentation, leaving the insoluble particles behind.
15. Give two examples where decantation is used in daily life.
Answer:
• Washing rice and pulses
• Separating oil and water when kept undisturbed
16. Why does decantation not remove all impurities?
Answer:
Some fine or tiny particles remain mixed in the water and do not settle completely.
17. What is filtration?
Answer:
Filtration is separating insoluble solid impurities from a liquid using a filter paper, cloth, or strainer.
18. What is the difference between filtration and decantation?
Answer:
Filtration removes even tiny insoluble particles using a filter, while decantation only separates large particles that settle down.
19. Name two materials used as filters besides filter paper.
Answer:
• Charcoal
• Cotton cloth
• Sand
(Any two)
20. What is churning?
Answer:
Churning is a process of vigorously stirring curd or cream to separate butter from buttermilk.
21. Why does butter float on top during churning?
Answer:
Butter is lighter than buttermilk, so it floats.
22. Name the instrument used traditionally to churn curd.
Answer:
Mathni (a wooden churner).
23. What is magnetic separation? Give an example.
Answer:
Magnetic separation uses magnets to separate magnetic substances from a mixture.
Example: Separating iron nails from sawdust.
24. Why can only iron nails be removed using a magnet from sawdust?
Answer:
Because iron is magnetic, while sawdust is non-magnetic.
25. Write one use of magnets in industries.
Answer:
Scrap iron is separated from heaps of waste using large industrial magnets.
26. What is the principle used in tea bags?
Answer:
Filtration. The tea leaves remain inside the bag, while the flavoured water passes through its tiny pores.
27. Why do fishermen use nets with holes?
Answer:
The holes allow water to pass through but trap fish. This works like filtration.
28. Describe how salt is obtained from seawater.
Answer:
Seawater is kept in shallow pits → water evaporates under the Sun → salt crystals remain → salt is collected and purified.
29. Give two examples where evaporation is used at home.
Answer:
• Drying clothes
• Drying pickles in sunlight
• Thickening milk (any two)
30. What is the purpose of the “WISE FISH” activity in the chapter?
Answer:
To help students match methods of separation with their correct uses in a fun and engaging way.
31. Which separation methods are used to prepare herbal kadha (Ayurvedic remedy)?
Answer:
• Handpicking
• Washing
• Boiling
• Filtration
• Evaporation
32. Why are medicinal herbs dried before use?
Answer:
To evaporate extra moisture and retain the useful medicinal part.
33. Milk has turned sour. Which separation method helps prepare paneer?
Answer:
Filtration after curdling.
Milk is heated → lemon added → curd forms → filtered → paneer obtained.
34. Why does salt dissolve in water but sawdust floats?
Answer:
Salt dissolves because it is soluble. Sawdust floats because it is light and insoluble.
35. How can polluted river water affect fish?
Answer:
• Plastic gets stuck in their mouths
• Fish may swallow harmful waste
• Reduced oxygen level
• Illness or death
36. List the different methods of separation used in the chapter.
Answer:
• Handpicking
• Threshing
• Winnowing
• Sieving
• Sedimentation
• Decantation
• Filtration
• Evaporation
• Churning
• Magnetic separation
37. When is sieving preferred over winnowing?
Answer:
When both components of the mixture are solids but of different sizes.
38. Why can’t we separate salt from seawater using filtration?
Answer:
Salt is dissolved (soluble), and dissolved solids cannot be removed by filtration.
39. What separation method is used in washing machines?
Answer:
• Sedimentation (dirty particles settle)
• Centrifugation (spinning separates water from clothes)
40. Why should mixtures with harmful impurities be separated?
Answer:
To ensure safety, prevent diseases, and make food fit for consumption.
41. Explain how you would separate a mixture of salt, sand and iron filings.
Answer:
• Step 1: Use a magnet → remove iron filings
• Step 2: Add water → salt dissolves, sand settles
• Step 3: Decantation/filtration → remove sand
• Step 4: Evaporation → obtain salt crystals
42. Why do we not use handpicking for separating wheat from flour?
Answer:
Because flour particles are too tiny and cannot be picked by hand.
43. How is condensation related to evaporation?
Answer:
Evaporation converts liquid into vapour.
Condensation converts vapour back into liquid.
44. Why is magnetic separation useful in recycling industries?
Answer:
Because iron pieces must be removed from waste before recycling plastic, paper, or wood.
45. How is filtration performed using cloth?
Answer:
The cloth has tiny pores that allow water to pass but trap large impurities.
46. Why is filtration better than decantation for muddy water?
Answer:
Filtration removes fine mud particles that do not settle completely.
47. What separation method is used in tea preparation? Why?
Answer:
Filtration using a tea strainer to remove insoluble tea leaves.
48. Why is evaporation used to obtain salt but not to obtain sugar from solution in this chapter?
Answer:
Salt occurs naturally in seawater and is easy to crystallize. Sugar crystallization needs more controlled heating.
49. How is evaporation used in nature?
Answer:
It is part of the water cycle where water evaporates from oceans, rivers and ponds.
50. Why is understanding separation methods important for daily life?
Answer:
Because they help in cooking, cleaning, farming, water purification, recycling and many home activities.
A. VERY SHORT ANSWER QUESTIONS (1 mark)
1. What is a mixture?
Answer: A mixture is a combination of two or more substances that are not chemically combined.
2. Name the method used to separate stones from rice.
Answer: Handpicking.
3. Which method is used to separate grains from stalks?
Answer: Threshing.
4. Name the method used to separate husk from wheat.
Answer: Winnowing.
5. What is the process of settling down of heavier impurities called?
Answer: Sedimentation.
6. What is the process of gently pouring clear liquid after sedimentation called?
Answer: Decantation.
7. What separation method does a tea strainer use?
Answer: Filtration.
8. Which method is used to obtain salt from seawater?
Answer: Evaporation.
9. Which separation method uses magnets?
Answer: Magnetic separation.
10. What is churning used for?
Answer: Separating butter from curd.
B. SHORT ANSWER TYPE QUESTIONS (2–3 marks)
1. What is handpicking? When is it used?
Answer:
Handpicking is the manual removal of unwanted substances based on differences in size, shape or color.
It is used when impurities are present in small quantities and can be easily picked by hand.
2. Explain winnowing with an example.
Answer:
Winnowing uses wind to separate lighter and heavier components.
Example: Separating husk (light) from wheat grains (heavy).
3. How does sieving work? Give one household example.
Answer:
Sieving uses a sieve with holes to separate larger and smaller particles.
Example: Removing bran from wheat flour.
4. What is filtration? Give two examples.
Answer:
Filtration separates insoluble solids from liquids using a filter.
Examples:
• Separating tea leaves from tea
• Filtering muddy water using cloth or filter paper
5. Distinguish between sedimentation and decantation.
Answer:
Sedimentation: Heavier particles settle at the bottom.
Decantation: Clear liquid is poured off after sedimentation.
6. Why is evaporation used to obtain salt from seawater?
Answer:
Because seawater contains dissolved salt; when water evaporates under the Sun, salt remains behind.
7. What is magnetic separation? Give an example.
Answer:
Magnetic separation uses magnets to remove magnetic materials.
Example: Separating iron nails from sawdust.
8. Why is filtration preferred over decantation for muddy water?
Answer:
Filtration removes fine impurities that do not settle during sedimentation.
C. LONG ANSWER TYPE QUESTIONS (4–6 marks)
1. Describe any four methods of separation with suitable examples.
Answer:
• Handpicking: Used to remove stones from grains.
• Threshing: Used to separate grains from stalks by beating the crop.
• Winnowing: Wind separates husk from grains.
• Sieving: Removes stones from sand or bran from flour.
2. Explain the steps involved in separating a mixture of sand, salt and iron filings.
Answer:
Step 1: Use a magnet → remove iron filings.
Step 2: Add water → salt dissolves; sand settles.
Step 3: Filter → sand remains.
Step 4: Evaporate the salt water → salt crystals obtained.
3. What is filtration? Explain the working of filtration using filter paper and a funnel.
Answer:
Filtration is separating insoluble particles using a filter.
• Fold filter paper into a cone
• Fix it in a funnel
• Pour muddy water
• Mud remains as residue
• Clean water collected in flask as filtrate
4. How do farmers separate grains from harvested crops? Explain threshing and winnowing in detail.
Answer:
• Threshing: The crop is beaten to detach grains from stalks.
• Winnowing: Wind separates lighter husk from heavier grains.
D. HIGHER ORDER THINKING SKILLS (HOTS) QUESTIONS
1. Valli cannot separate husk from rice in a closed room. Why?
Answer:
Because winnowing needs blowing air; in a closed room, there is no airflow to carry away the lighter husk.
2. Which method will you suggest to separate plastic pieces mixed with iron nails? Why?
Answer:
Magnetic separation, because only iron nails will get attracted to a magnet.
3. Why does tea strainer not work for salt solution?
Answer:
Because salt is dissolved in water and dissolved solids cannot be filtered.
4. Why does butter float during churning?
Answer:
Butter is lighter than buttermilk.
E. ACTIVITY-BASED QUESTIONS
1. In Activity 9.1, why do peanut skins fly away when blown?
Answer:
Peanut skins are lighter than peanuts, so the wind carries the skins away, leaving heavy peanuts behind.
2. What did you observe in Activity 9.2 after salt solution dried on paper?
Answer:
White patches appeared because water evaporated leaving behind salt crystals.
3. In Activity 9.4 filtration, what remains as residue and what collects as filtrate?
Answer:
Mud remains on filter paper as residue.
Clear water collects in flask as filtrate.
F. APPLICATION-BASED QUESTIONS
1. Milk has turned sour. Which separation method helps to make paneer? Explain.
Answer:
Filtration.
Heat sour milk → curd formation → filter using cloth → paneer collected as residue.
2. A fisherman catches fish using a net. Which separation principle is used?
Answer:
Filtration.
Water passes through holes; fish are trapped.
3. Clothes dry faster in sunlight. Which process is involved?
Answer:
Evaporation of water from wet clothes.
4. A shopkeeper wants to purify muddy honey. Which method should he use?
Answer:
Filtration using muslin cloth.
G. DIFFERENTIATION QUESTIONS
1. Differentiate between soluble and insoluble substances.
Answer:
Soluble: Dissolve in water (salt, sugar).
Insoluble: Do not dissolve in water (sand, stones).
2. Difference between filtration and winnowing.
Answer:
Filtration: Uses filter; separates solid-liquid.
Winnowing: Uses wind; separates light-heavy solids.
3. Difference between evaporation and condensation.
Answer:
Evaporation: Liquid → vapour.
Condensation: Vapour → liquid.
4. Handpicking vs Sieving.
Answer:
Handpicking: Done manually; used when impurities are few.
Sieving: Uses sieve; separates particles of different sizes.
H. DIAGRAM / REASONING-BASED QUESTIONS
1. Why does husk fall farther away from the tray during winnowing?
Answer:
Husk is lighter and gets blown away by the wind, falling far; grains are heavier and fall near the tray.
2. In filtration diagram (filter paper + funnel), why is filter paper folded into a cone?
Answer:
To increase surface area, fit properly in funnel, and allow water to pass while trapping impurities.
3. Explain why mud settles at the bottom of a glass of muddy water.
Answer:
Because mud particles are heavier and cannot remain suspended, so they settle due to gravity.
I. EXTRA NCERT VALUE-BASED QUESTIONS
1. Why is it important to keep rivers free from plastic waste?
Answer:
Because plastic harms aquatic life, pollutes water, blocks rivers, and affects human health.
2. What values do you learn from Malli and Valli’s curiosity in the chapter?
Answer:
Curiosity, observation, learning by doing, and understanding the science behind everyday activities.
3. How does separation of waste help the environment?
Answer:
It allows recycling, reduces landfill waste, saves energy, and prevents pollution.
4. Why should we respect farmers who perform separation work manually?
Answer:
Because they work hard to provide clean food and use traditional knowledge to ensure food quality.