Class 9 Science Chapter 5 MCQ
Exploring Mixtures and Their Separation
50 MCQs | 5 Sets | Answers Included
Set 1: Mixtures, Solutions and Concentration
Questions 1–10
1. A mixture that has the same composition throughout is called:
Show Answer
Answer: (B) Homogeneous mixture
2. Which of the following is a heterogeneous mixture?
Show Answer
Answer: (D) Sand mixed with water
3. In a salt solution, the substance that dissolves is called the:
Show Answer
Answer: (A) Solute
4. In a solution made by dissolving sugar in water, water is the:
Show Answer
Answer: (C) Solvent
5. Which of these is generally a homogeneous mixture?
Show Answer
Answer: (B) Air
6. The concentration of a solution describes:
Show Answer
Answer: (D) The amount of solute in a given amount of solution or solvent
7. What is the mass percentage of a solution containing 10 g of salt and 90 g of water?
Show Answer
Answer: (A) 10%. Mass of solution = 100 g; mass percentage = 10/100 × 100.
8. A solution contains 5 g of glucose in 100 mL of solution. Its mass-by-volume percentage is:
Show Answer
Answer: (C) 5% m/v
9. Volume-by-volume percentage is particularly suitable for expressing the concentration of:
Show Answer
Answer: (B) Two liquids
10. Which statement about a pure substance is correct?
Show Answer
Answer: (D) It has a definite composition and characteristic properties
Set 2: Solubility and Crystallisation
Questions 11–20
11. The maximum amount of a solute that dissolves in a specified amount of solvent at a given temperature is related to its:
Show Answer
Answer: (C) Solubility
12. A solution that can dissolve more solute at the same temperature is called:
Show Answer
Answer: (A) Unsaturated solution
13. A saturated solution at a particular temperature:
Show Answer
Answer: (D) Contains the maximum amount of dissolved solute under the stated conditions
14. The solubility of many solid substances in water generally:
Show Answer
Answer: (B) Increases as temperature rises, although exceptions exist.
15. For most gases dissolved in liquids, increasing the temperature generally:
Show Answer
Answer: (C) Decreases gas solubility
16. A graph showing how solubility changes with temperature is called a:
Show Answer
Answer: (A) Solubility curve
17. A saturated solution contains 60 g of solute per 100 g of water at a higher temperature and 40 g at a lower temperature. How much solute separates out when it cools, assuming no solvent is lost?
Show Answer
Answer: (D) 20 g. The difference in solubility is 60 − 40 = 20 g.
18. The process of obtaining solid crystals from a suitable solution is called:
Show Answer
Answer: (B) Crystallisation
19. Crystallisation can help purify a solid because:
Show Answer
Answer: (C) The desired substance can form crystals while many impurities remain in solution
20. Why is a hot saturated solution sometimes allowed to cool slowly during crystallisation?
Show Answer
Answer: (A) To encourage crystals to grow gradually
Set 3: Distillation and Chromatography
Questions 21–30
21. Which method can separate a dissolved solid from a liquid by recovering the solvent?
Show Answer
Answer: (D) Distillation
22. During simple distillation, a liquid is first converted into vapour by:
Show Answer
Answer: (B) Heating
23. In a distillation apparatus, the condenser is used to:
Show Answer
Answer: (A) Cool vapour so it becomes liquid
24. Which technique is commonly used to separate miscible liquids with relatively close boiling points?
Show Answer
Answer: (C) Fractional distillation
25. Crude petroleum is separated into useful fractions mainly by:
Show Answer
Answer: (D) Fractional distillation
26. Paper chromatography separates mixture components because they:
Show Answer
Answer: (B) Move differently between the mobile and stationary phases
27. Which mixture can be investigated using paper chromatography?
Show Answer
Answer: (A) Pigments in ink
28. At the beginning of a paper chromatography experiment, the sample spot should normally be:
Show Answer
Answer: (C) Above the solvent level
29. Why is pencil often used to draw the baseline in paper chromatography?
Show Answer
Answer: (B) Graphite generally does not travel with the solvent like many inks do
30. Which statement correctly describes evaporation?
Show Answer
Answer: (D) A liquid changes into vapour from its surface
Set 4: Separation Techniques in Everyday Life
Questions 31–40
31. Which apparatus is suitable for separating two immiscible liquids such as oil and water?
Show Answer
Answer: (A) Separating funnel
32. Oil usually forms the upper layer when mixed with water because it is:
Show Answer
Answer: (C) Less dense than water
33. Which technique separates an insoluble solid from a liquid using a porous barrier?
Show Answer
Answer: (B) Filtration
34. What is the solid left on filter paper called?
Show Answer
Answer: (D) Residue
35. Which method can separate iron filings from a mixture containing sand?
Show Answer
Answer: (A) Magnetic separation
36. Which process can separate a substance that changes directly from solid to vapour on heating from a non-sublimable solid?
Show Answer
Answer: (C) Sublimation
37. Which mixture can be separated using sublimation under suitable conditions?
Show Answer
Answer: (B) Camphor mixed with sand
38. Which method uses rapid spinning to help separate suspended particles from a liquid?
Show Answer
Answer: (D) Centrifugation
39. Centrifugation is commonly used in laboratories to separate:
Show Answer
Answer: (A) Components of blood
40. When muddy water is left undisturbed, heavier suspended particles settle at the bottom. This process is called:
Show Answer
Answer: (C) Sedimentation
Set 5: Suspensions, Colloids and Concept Review
Questions 41–50
41. Which of the following is an example of a suspension?
Show Answer
Answer: (B) Sand in water
42. What generally happens to the particles of a suspension when it is left undisturbed?
Show Answer
Answer: (D) They settle down over time
43. Which of the following is an example of a colloid?
Show Answer
Answer: (A) Milk
44. The scattering of light by colloidal particles is known as:
Show Answer
Answer: (C) Tyndall effect
45. Which statement best distinguishes a true solution from a suspension?
Show Answer
Answer: (B) A true solution has uniformly distributed dissolved particles and does not settle on standing
46. Assertion (A): A homogeneous mixture has a uniform composition throughout.
Reason (R): Its components are distributed uniformly at the scale of observation.
Show Answer
Answer: (A) Both A and R are true, and R correctly explains A.
47. Assertion (A): Oil and water can usually be separated using a separating funnel.
Reason (R): Oil and water are immiscible and form separate layers.
Show Answer
Answer: (A) Both A and R are true, and R correctly explains A.
48. Assertion (A): A suspension can often be separated by filtration.
Reason (R): Suspended particles can be large enough to be retained by a suitable filter.
Show Answer
Answer: (A) Both A and R are true, and R correctly explains A.
49. Assertion (A): Fractional distillation can separate liquid components with relatively close boiling points.
Reason (R): A fractionating column allows repeated vaporisation and condensation, improving separation.
Show Answer
Answer: (A) Both A and R are true, and R correctly explains A.
50. Which method is most suitable for separating different coloured dyes in an ink sample?
Show Answer
Answer: (C) Paper chromatography