Material Around Us Part 2: MCQs (Q26–Q50)
Part 2 — Questions 26–50 (Mixtures & separation, soluble/insoluble, sieving, filtration, magnet)
26. A mixture of sand and water can be separated by which method?
A. Distillation
B. Filtration ← Correct answer: B
C. Chromatography
D. Electrolysis
Explanations:
A) Distillation separates based on boiling points (not suitable for sand-water).
B) Correct — filtration retains sand, lets water pass.
C/D) Not appropriate here.
27. Which of the following is a solution?
A. Sand in water
B. Oil in water
C. Muddy water
D. Sugar dissolved in water ← Correct answer: D
Explanations:
A/B/C) Suspensions or emulsions (not true solutions).
D) Correct — sugar molecules dissolve uniformly forming a solution.
28. Which technique separates a soluble solid from its solution to obtain the solid?
A. Filtration
B. Sieving
C. Evaporation/crystallisation ← Correct answer: C
D. Magnetism
Explanations:
A) Removes insoluble solids.
B) Removes coarse particles by size.
C) Correct — evaporating solvent leaves behind dissolved solid.
D) Only for magnetic solids.
29. How would you separate iron filings mixed with sand?
A. Filter through cloth
B. Use a magnet to attract the iron filings ← Correct answer: B
C. Evaporate mixture
D. Distil it
Explanations:
A) Cloth cannot separate tiny iron from sand.
B) Correct — magnet picks magnetic iron out of sand.
C/D) Not suitable.
30. Tea leaves are separated from tea by which method?
A. Chromatography
B. Evaporation
C. Filtration (through a sieve or strainer) ← Correct answer: C
D. Centrifugation only
Explanations:
A) Not typical for making tea.
B) Evaporation would remove water.
C) Correct — strainer/filtration retains leaves, passes liquid.
D) Unnecessary in household tea making.
31. Which mixture is homogeneous?
A. Sand + water
B. Salt dissolved in water ← Correct answer: B
C. Oil + water
D. Gravel + sand
Explanations:
A/C/D) Heterogeneous mixtures (components visible/separate).
B) Correct — salt solution is uniform throughout (homogeneous solution).
32. Which method is used to separate milk into cream and milk solids?
A. Magnetism
B. Centrifugation ← Correct answer: B
C. Sieving
D. Simple filtration
Explanations:
A/C/D) Ineffective.
B) Correct — centrifuge separates components based on density (industry uses cream separators).
33. Which of the following pairs can be separated by decantation?
A. Salt in water (dissolved)
B. Oil floating on water ← Correct answer: B
C. Alcohol mixed with water
D. Copper and zinc alloy
Explanations:
A) Salt is dissolved — cannot decant to separate solid.
B) Correct — pouring off top layer (oil) separates it from lower aqueous layer.
C) Requires distillation.
D) Requires metallurgical methods.
34. During filtration, what passes through the filter paper?
A. Insoluble solids only
B. Filtrate (liquid and dissolved substances) ← Correct answer: B
C. Pieces of stone only
D. Whole solid mixture unchanged
Explanations:
A/C/D) Incorrect.
B) Correct — filtrate comprises liquid and dissolved solutes; residue remains on filter.
35. Which method would you use to separate colored components of ink?
A. Sieving
B. Paper chromatography ← Correct answer: B
C. Filtration
D. Evaporation only
Explanations:
A/C/D) Not suitable for separating pigments.
B) Correct — chromatography separates substances based on solubility and capillary action.
36. Which of the following is true about suspensions?
A. Components do not settle out on standing
B. Components settle out on standing (can be separated by filtration/decantation) ← Correct answer: B
C. They are always transparent
D. They are the same as solutions
Explanations:
A) Incorrect — that’s true for solutions/colloids.
B) Correct — muddy water is a suspension that settles.
C/D) Incorrect.
37. Which substance is insoluble in water?
A. Salt
B. Sugar
C. Sand ← Correct answer: C
D. Vinegar
Explanations:
A/B/D) Soluble substances.
C) Correct — sand does not dissolve; it forms a suspension.
38. To separate a mixture of two liquids with different boiling points you use
A. Filtration
B. Sieving
C. Distillation ← Correct answer: C
D. Magnet
Explanations:
A/B/D) Not suitable.
C) Correct — distillation separates liquids by boiling point.
39. Which statement about colloids is correct?
A. Colloids have very large particles that settle rapidly
B. Colloids have particles that do not settle easily and cannot be filtered by ordinary filter paper ← Correct answer: B
C. Colloids are the same as solutions
D. Colloids are always transparent and colourless
Explanations:
A) Incorrect — they are intermediate in size and remain dispersed.
B) Correct — colloids like milk scatter light but do not settle.
C/D) Wrong generalizations.
40. Which is the correct order to separate a mixture of sand, salt and iron filings?
A. Evaporate salt, then magnet, then filter
B. Use magnet (remove iron), then add water and filter (remove sand), then evaporate water (retrieve salt) ← Correct answer: B
C. Filtration, magnetism, filtration again
D. Chromatography, distillation, magnetism
Explanations:
A) Wrong order — you can’t evaporate salt before removing iron/sand.
B) Correct — magnet first removes iron; sand is insoluble so comes out on filtration; salt recovered by evaporation.
C/D) Inefficient/incorrect.
41. Which separation method is best to remove pebbles from sand?
A. Filtration through filter paper
B. Sieving through a mesh (sieve) ← Correct answer: B
C. Distillation
D. Magnetic separation
Explanations:
A) Filter paper is too fine and would not be practical for pebbles.
B) Correct — sieving separates by particle size.
C/D) Not appropriate.
42. Salt in seawater can be obtained by which process (sunlight assisted)?
A. Filtration only
B. Evaporation/crystallisation in salt pans ← Correct answer: B
C. Magnetism
D. Chromatography
Explanations:
A/C/D) Not appropriate.
B) Correct — letting water evaporate leaves salt crystals.
43. Which of these mixtures is homogeneous?
A. Oil and water
B. Flour and sand
C. Vinegar (acetic acid) in water ← Correct answer: C
D. Water and pebbles
Explanations:
A/B/D) Heterogeneous.
C) Correct — vinegar dissolves uniformly in water creating a homogeneous solution.
44. A mixture of oil and water can be separated using
A. Filter paper only
B. Separation funnel or decantation (due to immiscibility and density difference) ← Correct answer: B
C. Evaporation of water (would leave oil behind but impractical)
D. Paper chromatography only
Explanations:
A/D) Not suitable.
B) Correct — oil floats on water; decantation or separation funnel separates layers.
C) Theoretically possible but inefficient and may change oil.
45. Which method separates tea leaves from tea liquor most commonly?
A. Centrifugation
B. Filtration (strainer/tea filter) ← Correct answer: B
C. Distillation
D. Magnetic separation
Explanations:
A/C/D) Not typical for making tea.
B) Correct — filtration/straining retains leaves.
46. Which of these techniques uses centrifugal force to speed up separation?
A. Sieving
B. Filtration using paper
C. Centrifugation ← Correct answer: C
D. Decantation only
Explanations:
A/B) Mechanical separation by size or porous barrier.
C) Correct — centrifuge spins at high speed to separate based on density.
D) Slower gravity-based process.
47. Which of the following is a heterogeneous mixture?
A. Salt solution
B. Sugar solution
C. Sand in water ← Correct answer: C
D. Vinegar in water
Explanations:
A/B/D) Homogeneous solutions.
C) Correct — sand particles remain distinct in water.
48. Which property allows a magnet to separate iron filings from a mixture?
A. Solubility
B. Malleability
C. Magnetism ← Correct answer: C
D. Boiling point
Explanations:
A/B/D) Irrelevant.
C) Correct — magnetic attraction isolates ferromagnetic particles.
49. When a mixture of two miscible liquids with different boiling points is separated, the process is called
A. Filtration
B. Distillation ← Correct answer: B
C. Sieving
D. Adsorption
Explanations:
A/C/D) Not correct for liquids separation by boiling point.
B) Correct — fractional/distillation separates miscible liquids by boiling point.
50. Which is the simplest way to separate leaves from water after boiling vegetable stock?
A. Evaporation until leaves burn
B. Filtration through a strainer or sieve ← Correct answer: B
C. Chromatography
D. Magnetic separation
Explanations:
A/C/D) Not practical or safe.
B) Correct — strainer removes solid leaves leaving liquid stock.