📘 CBSE Class 9 Science – Is Matter Around Us Pure

📝 Part 3: MCQs (Q51–Q75)

Q51. Which of these will NOT scatter light?

A) Milk
B) Starch solution
C) Sugar solution
D) Fog

✅ Answer: C) Sugar solution

• A) Incorrect: Milk is colloid → scatters light.
• B) Incorrect: Starch solution is colloid → scatters.
• C) Correct: True solution → no scattering.
• D) Incorrect: Fog scatters light strongly.

Q52. Which property is common for compounds?

A) They have variable composition
B) They retain properties of components
C) They are formed by chemical combination
D) They can be separated physically

✅ Answer: C) They are formed by chemical combination

• A) Incorrect: Compounds have fixed composition.
• B) Incorrect: They lose properties of elements.
• C) Correct: Compounds form by chemical reaction.
• D) Incorrect: Cannot be separated physically.

Q53. Sand and iron filings can be separated by:

A) Filtration
B) Magnet
C) Evaporation
D) Sedimentation

✅ Answer: B) Magnet

• A, C, D) Incorrect: Not suitable.
• B) Correct: Iron filings attracted by magnet.

Q54. Which method separates alcohol and water?

A) Filtration
B) Fractional distillation
C) Evaporation
D) Decantation

✅ Answer: B) Fractional distillation

• A) Incorrect: Not for liquids.
• B) Correct: Alcohol and water have different boiling points.
• C, D) Incorrect: Ineffective.

Q55. Which of the following is a heterogeneous mixture?

A) Steel
B) Brass
C) Soil
D) Air

✅ Answer: C) Soil

• A, B, D) Incorrect: All homogeneous.
• C) Correct: Soil is non-uniform.

Q56. The process of settling down of heavier particles in a liquid is called:

A) Filtration
B) Sedimentation
C) Decantation
D) Evaporation

✅ Answer: B) Sedimentation

• A) Incorrect: Filtration uses filter.
• B) Correct: Heavy particles settle down by sedimentation.
• C) Incorrect: Decantation is pouring off liquid.
• D) Incorrect: Evaporation removes solvent.

Q57. Which separation technique is used to obtain pure solvent from solution?

A) Evaporation
B) Distillation
C) Filtration
D) Chromatography

✅ Answer: B) Distillation

• A) Incorrect: Leaves solute, not pure solvent.
• B) Correct: Distillation collects solvent vapour and condenses it.
• C, D) Incorrect: Not suitable.

Q58. Which type of mixture shows Tyndall effect?

A) True solution
B) Colloid
C) Suspension
D) Pure substance

✅ Answer: B) Colloid

• A, D) Incorrect: Do not scatter light.
• B) Correct: Colloids scatter light.
• C) Incorrect: Suspensions scatter but particles are visible.

Q59. An example of solid solution is:

A) Air
B) Brass
C) Sugar in water
D) Fog

✅ Answer: B) Brass

• A) Incorrect: Gas solution.
• B) Correct: Solid + solid solution (copper + zinc).
• C) Incorrect: Liquid solution.
• D) Incorrect: Colloid.

Q60. Which is not a property of a compound?

A) Components can be separated by chemical methods
B) It has a fixed ratio
C) Properties differ from constituents
D) Components retain original properties

✅ Answer: D) Components retain original properties

• A, B, C) Correct properties of compounds.
• D) Correct answer: Components lose original properties in compounds.

Q61. Which method separates salt and ammonium chloride?

A) Filtration
B) Sublimation
C) Evaporation
D) Chromatography

✅ Answer: B) Sublimation

• A, C, D) Incorrect: Not suitable.
• B) Correct: NH₄Cl sublimes, salt does not.

Q62. Which mixture is separated by separating funnel?

A) Salt + water
B) Oil + water
C) Sand + water
D) Alcohol + water

✅ Answer: B) Oil + water

• A, C, D) Incorrect: Different techniques needed.
• B) Correct: Immiscible liquids separate in funnel.

Q63. The process of removing water from sugar solution by heating is called:

A) Sedimentation
B) Evaporation
C) Distillation
D) Filtration

✅ Answer: B) Evaporation

• A, C, D) Incorrect: Not suitable.
• B) Correct: Solvent evaporates, sugar left behind.

Q64. Which one is a colloid?

A) Sugar solution
B) Salt solution
C) Blood
D) Alcohol solution

✅ Answer: C) Blood

• A, B, D) Incorrect: True solutions.
• C) Correct: Blood is a colloid (plasma medium + cells).

Q65. Which is NOT a method to separate mixtures?

A) Distillation
B) Filtration
C) Chromatography
D) Combustion

✅ Answer: D) Combustion

• A, B, C) Correct separation techniques.
• D) Correct answer: Combustion is chemical change, not separation.

Q66. In a true solution, particles are:

A) Visible with naked eye
B) Visible under microscope
C) Invisible and do not scatter light
D) Large and settle down

✅ Answer: C) Invisible and do not scatter light

• A, B, D) Incorrect: Not true for solutions.
• C) Correct: True solutions are transparent.

Q67. Which method separates nitrogen from liquid air?

A) Evaporation
B) Fractional distillation
C) Filtration
D) Chromatography

✅ Answer: B) Fractional distillation

• A, C, D) Incorrect: Not suitable.
• B) Correct: Liquefied air separated by boiling points.

Q68. Bronze is an alloy of:

A) Copper + Zinc
B) Copper + Tin
C) Iron + Carbon
D) Nickel + Chromium

✅ Answer: B) Copper + Tin

• A) Incorrect: That’s brass.
• B) Correct: Bronze = Cu + Sn.
• C, D) Incorrect: Other alloys.

Q69. The continuous medium in fog is:

A) Water
B) Air
C) Smoke
D) Dust

✅ Answer: B) Air

• A) Incorrect: Water is dispersed phase.
• B) Correct: Air = medium, water droplets dispersed.
• C, D) Incorrect: Not relevant.

Q70. Which is NOT a colloid?

A) Blood
B) Smoke
C) Salt solution
D) Fog

✅ Answer: C) Salt solution

• A, B, D) Incorrect: All colloids.
• C) Correct: Salt solution is true solution.

Q71. Which method separates pigments from leaves?

A) Chromatography
B) Filtration
C) Centrifugation
D) Distillation

✅ Answer: A) Chromatography

• A) Correct: Plant pigments separated by chromatography.
• B, C, D) Incorrect: Not suitable.

Q72. Which mixture cannot be separated by filtration?

A) Sand + water
B) Mud + water
C) Salt + water
D) Chalk + water

✅ Answer: C) Salt + water

• A, B, D) Incorrect: Insoluble solids separated by filtration.
• C) Correct: Salt solution passes through filter → cannot separate.

Q73. The dispersed phase in smoke is:

A) Liquid
B) Solid
C) Gas
D) Plasma

✅ Answer: B) Solid

• A, C, D) Incorrect: Not applicable.
• B) Correct: Smoke = solid particles dispersed in air.

Q74. Which separation method is used in laundries for drying clothes?

A) Evaporation
B) Distillation
C) Centrifugation
D) Filtration

✅ Answer: C) Centrifugation

• A, B, D) Incorrect: Not used.
• C) Correct: Clothes dried by centrifugal dryers.

Q75. The colloid used in paints is:

A) Gas in gas
B) Solid in liquid
C) Liquid in liquid
D) Solid in gas

✅ Answer: B) Solid in liquid

• A, C, D) Incorrect: Not applicable.
• B) Correct: Paint = solid particles in liquid medium.

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