Presented by BodhiClasses – your digital learning partner for NCERT-based conceptual clarity and smart revision tools. This post on Methods of Separation solves the NCERT Textbook Questions in the most lucid manner.
1. What purpose does handpicking serve in the process of separation?
(i) Filtration
(ii) Sorting
(iii) Evaporation
(iv) Decantation
✅ Answer: (ii) Sorting
Explanation: Handpicking is used to sort out unwanted solid particles like stones or twigs from food grains manually based on visible differences.
2. Which of the following substances are commonly separated using the churning method?
(i) Oil from water
(ii) Sand from water
(iii) Cream from milk
(iv) Oxygen from air
✅ Answer: (iii) Cream from milk
Explanation: Churning is used to separate butter or cream, which floats on curd or milk due to its lower density.
3. Which factor is usually essential for the filtration?
(i) Apparatus size
(ii) Presence of air
(iii) Pore size
(iv) Temperature of the mixture
✅ Answer: (iii) Pore size
Explanation: The pore size of the filter determines what particles are blocked and what passes through.
4. State with reason(s) whether the following statements are True [T] or False [F]. Also, correct the False statement(s).
(i) Salt can be separated from salt solution by keeping it under the Sun.
✅ True – Evaporation helps in separating salt as water evaporates.
(ii) Handpicking should be used only when the quantity of one component is less.
✅ True – It is suitable for small-scale separation.
(iii) A mixture of puffed rice and rice grains can be separated by threshing.
❌ False – Threshing is for separating grains from stalks, not for this mixture.
✅ Corrected: The mixture of puffed rice and rice grains can be separated by winnowing due to weight difference.
(iv) A mixture of mustard oil and lemon water can be separated by decantation.
✅ True – Oil and water do not mix and can be separated when settled.
(v) Sieving is used to separate a mixture of rice flour and water.
❌ False – Sieving works on solid-solid mixtures, not solid-liquid.
✅ Corrected: This mixture should be separated by filtration.
5. Match the mixtures in Column I with their method of separation in Column II.
| Column I (Mixture) | Column II (Separation Method) |
|---|---|
| (i) Gram flour mixed with black gram | (a) Handpicking |
| (ii) Chalk powder mixed with water | (e) Filtration |
| (iii) Corn mixed with potatoes | (d) Sieving |
| (iv) Iron powder mixed with sawdust | (b) Magnetic separation |
| (v) Oil mixed with water | (c) Decantation |
6. In what situations would you use decantation instead of filtration to separate solids from liquids?
✅ Answer: Decantation is used when the solid particles are heavy and settle at the bottom of the liquid (like sand in water). It is faster and simpler than filtration and used when a little impurity is acceptable.
7. Can you relate the presence of nasal hair to any separation process?
✅ Answer: Yes, nasal hair acts like a natural filter, trapping dust and larger airborne particles from entering the lungs. This is similar to filtration where solid particles are blocked by pores.
8. During the COVID-19 pandemic, all of us wore masks. Generally, what material are they made of? What is the role of these masks?
✅ Answer: Most masks are made from non-woven fabric or filtering cloth like polypropylene. They act like a filter, trapping droplets and particles in the air, preventing the spread of viruses and protecting from infections.
9. A mixture containing potatoes, salt and sawdust has been given to you. Outline a stepwise procedure for separating each component from this mixture.
✅ Answer:
- Handpick the potatoes (large and visible solids).
- Dissolve the remaining mixture in water. Salt dissolves, sawdust floats.
- Skim or filter the sawdust from the top.
- Evaporate the water to get salt back.
10. Read the following story titled ‘Intelligent Leela’ and tick the most appropriate options. Provide a suitable title of your choice for the paragraph.
Title Suggestion: “Leela’s Clever Water Purification”
Correct Answers:
- Thirsty,
- Water,
- Unfit,
- Filtered,
- Boiled,
- Filtered,
- Fit
✅ Explanation: Leela correctly used sedimentation, filtration with cloth, boiling, and then filtering again to ensure the water was safe to drink.
