50 Very Short Answer Type Questions — Topic-wise

Concise answers follow each question for quick revision.

1. 1. What is sieving?Sieving separates particles based on size using a mesh or sieve.
2. 2. Give one example of sieving.Sifting flour to remove lumps is an example of sieving.
3. 3. What is filtration?Filtration separates an insoluble solid from a liquid using filter paper or cloth.
4. 4. Define residue and filtrate.Residue is the solid left on the filter; filtrate is the liquid that passes through.
5. 5. What is decantation?Decantation involves pouring off the liquid after the solid has settled by sedimentation.
6. 6. What is sedimentation?Sedimentation is the settling of heavier solid particles at the bottom of a liquid by gravity.
7. 7. How does evaporation separate mixtures?Evaporation removes a liquid as vapour leaving dissolved solids behind (e.g., salt from seawater).
8. 8. What is crystallisation?Crystallisation obtains pure crystals from a saturated solution by slow cooling or evaporation.
9. 9. When is crystallisation preferred over simple evaporation?When purer crystals are needed, crystallisation is preferred because it yields purer solids.
10. 10. What is distillation?Distillation separates liquids with different boiling points by vaporising and condensing them.
11. 11. Give one use of simple distillation.Obtaining fresh water from seawater by boiling and condensing the vapour.
12. 12. What is fractional distillation used for?Fractional distillation separates liquids with closer boiling points on a larger scale (e.g., petroleum fractions).
13. 13. What is magnetic separation?Magnetic separation removes magnetic materials (like iron filings) from non-magnetic ones using a magnet.
14. 14. Give an example of magnetic separation.Separating iron nails from a mixture of sand and nails with a magnet.
15. 15. What is centrifugation (simple)?Centrifugation spins mixtures to force denser particles to the bottom more quickly than by gravity.
16. 16. Where is centrifugation commonly used?In laboratories and hospitals to separate blood components.
17. 17. What does soluble mean?Soluble means a substance can dissolve in a particular solvent (e.g., salt in water).
18. 18. What does insoluble mean?Insoluble means a substance does not dissolve in a solvent (e.g., sand in water).
19. 19. How can you separate a mixture of sand and water?Use filtration to separate sand (residue) from water (filtrate).
20. 20. How can you extract salt from salty water?Evaporate the water or use distillation to collect pure water and leave salt behind.
21. 21. What is the filtrate when filtering a sand–water mixture?The filtrate is the clear water passing through the filter.
22. 22. What is the residue when filtering sand from water?The residue is the sand left on the filter paper.
23. 23. Why is filtration useful for purifying water?It removes suspended solids and visible impurities, making water clearer.
24. 24. What property does distillation exploit?Distillation exploits differences in boiling points of liquids.
25. 25. What is the distillate?Distillate is the liquid collected after condensation in distillation (usually purer component).
26. 26. What is meant by ‘saturation’ in a solution?A saturated solution contains the maximum amount of dissolved solute at that temperature.
27. 27. How does cooling affect a saturated hot solution?Cooling often causes excess solute to crystallise out as the solution becomes supersaturated.
28. 28. How can you separate oil and water (conceptual)?Use a separating funnel to let denser liquid settle and drain; oil and water form layers due to immiscibility.
29. 29. What is decantation useful for?Decantation is useful to remove liquid from settled solids without disturbing the sediment.
30. 30. Why does adding salt to ice make it melt?Salt lowers the freezing point of water, causing ice to melt by freezing point depression.
31. 31. What safety step is important during distillation?Operate under supervision, avoid open flames near flammable liquids, and use heat-resistant equipment.
32. 32. How can you separate ink components (simple demonstration)?Use paper chromatography to separate coloured components based on solubility and capillary action.
33. 33. What is sieving commonly used for in daily life?Sieving is used to remove stones from grains or sift flour while cooking.
34. 34. Which method separates very fine suspended particles that settle slowly?Centrifugation speeds up settling; filtration also removes fine suspended particles.
35. 35. What happens to impurities left after evaporation of a solution?They remain behind as solid residues (e.g., salt from seawater).
36. 36. Why is distillation better than evaporation to obtain pure water?Distillation condenses vapour into liquid, leaving volatile impurities and salts behind, yielding purer water.
37. 37. What is the role of filter paper in filtration?Filter paper traps solids while allowing liquid to pass through as filtrate.
38. 38. Give one household example of filtration.Using a cloth to strain tea leaves from tea is a household filtration example.
39. 39. How can magnetic separation help in recycling?Magnets remove ferrous metals from mixed waste, aiding recycling of metals.
40. 40. Why must we clean apparatus after separation experiments?To avoid contamination, ensure accurate results in future and maintain safety and hygiene.
41. 41. What is a soluble impurity?A soluble impurity dissolves in the solvent and may require evaporation or distillation to remove.
42. 42. What is an insoluble impurity?An insoluble impurity does not dissolve and can often be removed by filtration or sieving.
43. 43. How is salt obtained from seawater on a large scale?By solar evaporation in salt pans followed by crystallisation of salt.
44. 44. What is the first step to separate a mixture of sand, iron filings and salt?Use a magnet to remove iron filings first, then dissolve salt in water and filter to separate sand.
45. 45. What term describes the solid collected after filtration of a mixture?The collected solid is called the residue.
46. 46. What is the eco-friendly reason to separate and recycle materials?Recycling reduces waste, conserves resources and saves energy needed to produce new materials.
47. 47. How can you remove suspended clay from muddy water simply?Allow water to stand for sedimentation, then decant the clear water and filter if needed.
48. 48. What is the main advantage of centrifugation over sedimentation?Centrifugation is much faster and more effective for very small or slow-settling particles.
49. 49. Name a separation method useful in laboratories to purify chemicals.Distillation and crystallisation are commonly used to purify chemicals in laboratories.
50. 50. Why is understanding separation methods important in everyday life?They help purify water, prepare food, recycle materials and solve practical problems using simple scientific ideas.