Is Matter Around Us Pure Part 1: MCQs (Q1–Q25)
📘 CBSE Class 9 Science – Is Matter Around Us Pure
📝 Part 1: MCQs (Q1–Q25)
Q1. Which of the following is a pure substance?
A) Air
B) Brass
C) Distilled water
D) Milk
✅ Answer: C) Distilled water
- A) Incorrect: Air is a mixture of gases.
- B) Incorrect: Brass is an alloy (mixture of copper and zinc).
- C) Correct: Distilled water contains only H₂O molecules, hence pure.
- D) Incorrect: Milk is a colloid, not pure.
Q2. Which of the following is a mixture?
A) Oxygen
B) Carbon dioxide
C) Sodium chloride
D) Soil
✅ Answer: D) Soil
- A) Incorrect: Oxygen is an element.
- B) Incorrect: Carbon dioxide is a compound.
- C) Incorrect: NaCl is a compound.
- D) Correct: Soil contains many substances, hence a mixture.
Q3. Which method is used to separate cream from milk?
A) Distillation
B) Centrifugation
C) Filtration
D) Evaporation
✅ Answer: B) Centrifugation
- A) Incorrect: Distillation separates based on boiling point.
- B) Correct: Centrifugation separates components based on density.
- C) Incorrect: Filtration separates insoluble solids.
- D) Incorrect: Evaporation removes solvent.
Q4. Brass is a mixture of:
A) Copper and zinc
B) Copper and tin
C) Zinc and iron
D) Iron and carbon
✅ Answer: A) Copper and zinc
- A) Correct: Brass = copper + zinc alloy.
- B) Incorrect: Copper + tin = bronze.
- C) Incorrect: Zinc + iron is not brass.
- D) Incorrect: Iron + carbon = steel.
Q5. Which is NOT a homogeneous mixture?
A) Air
B) Salt solution
C) Sugar solution
D) Soil
✅ Answer: D) Soil
- A, B, C) Incorrect: All are uniform mixtures.
- D) Correct: Soil is heterogeneous, not uniform throughout.
Q6. Which method separates salt from sea water?
A) Sedimentation
B) Chromatography
C) Evaporation
D) Filtration
✅ Answer: C) Evaporation
- A) Incorrect: Sedimentation separates solids from liquids.
- B) Incorrect: Chromatography separates dissolved colors.
- C) Correct: Water evaporates, leaving salt behind.
- D) Incorrect: Filtration does not separate dissolved salt.
Q7. Which of the following is a colloid?
A) Salt solution
B) Milk
C) Copper sulphate solution
D) Distilled water
✅ Answer: B) Milk
- A) Incorrect: True solution, not colloid.
- B) Correct: Milk is emulsion (colloid).
- C) Incorrect: Copper sulphate solution is true solution.
- D) Incorrect: Pure substance, not colloid.
Q8. Tyndall effect is shown by:
A) Salt solution
B) Sugar solution
C) Milk
D) Distilled water
✅ Answer: C) Milk
- A) Incorrect: Salt solution = true solution, no scattering.
- B) Incorrect: Sugar solution also true solution.
- C) Correct: Colloids scatter light (Tyndall effect).
- D) Incorrect: Pure water does not scatter light.
Q9. Which separation technique is used in petrol refineries?
A) Sublimation
B) Fractional distillation
C) Filtration
D) Evaporation
✅ Answer: B) Fractional distillation
- A) Incorrect: Sublimation separates solid → gas substances.
- B) Correct: Fractional distillation separates miscible liquids (crude oil fractions).
- C) Incorrect: Filtration separates insoluble solids.
- D) Incorrect: Evaporation separates solid + liquid mixtures.
Q10. The particles in a true solution are:
A) Large and visible
B) Invisible but scatter light
C) Very small and do not scatter light
D) Settle on standing
✅ Answer: C) Very small and do not scatter light
- A) Incorrect: Not visible.
- B) Incorrect: That’s colloid property.
- C) Correct: True solution particles < 1 nm.
- D) Incorrect: True solution is stable.
Q11. Which method separates camphor from salt?
A) Filtration
B) Sublimation
C) Evaporation
D) Distillation
✅ Answer: B) Sublimation
- A) Incorrect: Filtration fails for solids in solids.
- B) Correct: Camphor sublimates, salt does not.
- C, D) Incorrect: Not suitable here.
Q12. Which of the following is NOT a mixture?
A) Brass
B) Air
C) Soil
D) Glucose
✅ Answer: D) Glucose
- A) Incorrect: Brass is an alloy (mixture).
- B) Incorrect: Air is a mixture.
- C) Incorrect: Soil is a mixture.
- D) Correct: Glucose is a pure compound (C₆H₁₂O₆).
Q13. Smoke is an example of:
A) Solid in gas (colloid)
B) Gas in gas
C) Liquid in gas
D) Gas in solid
✅ Answer: A) Solid in gas (colloid)
- A) Correct: Smoke = fine solid particles in air.
- B) Incorrect: Air itself is gas in gas.
- C) Incorrect: Fog is liquid in gas.
- D) Incorrect: Gas in solid is hydrogen in palladium.
Q14. Chromatography is used to:
A) Separate insoluble solids
B) Separate volatile liquids
C) Separate components of dyes
D) Separate cream from milk
✅ Answer: C) Separate components of dyes
- A) Incorrect: Filtration does this.
- B) Incorrect: Fractional distillation does this.
- C) Correct: Chromatography separates colors in inks.
- D) Incorrect: Centrifugation separates cream.
Q15. Which of these is a heterogeneous mixture?
A) Salt solution
B) Air
C) Soil
D) Brass
✅ Answer: C) Soil
- A) Incorrect: Salt solution is uniform.
- B) Incorrect: Air is homogeneous.
- C) Correct: Soil is non-uniform.
- D) Incorrect: Brass is homogeneous alloy.
Q16. Alloy is a:
A) Compound
B) Homogeneous mixture
C) Heterogeneous mixture
D) Element
✅ Answer: B) Homogeneous mixture
- A) Incorrect: Not chemically bonded like compounds.
- B) Correct: Uniform mixture of metals.
- C) Incorrect: Appears uniform, not heterogeneous.
- D) Incorrect: Not an element.
Q17. Which of the following will show Tyndall effect?
A) Salt solution
B) Sugar solution
C) Air
D) Starch solution
✅ Answer: D) Starch solution
- A, B) Incorrect: True solutions → no scattering.
- C) Incorrect: Air is homogeneous.
- D) Correct: Starch solution = colloid.
Q18. Distillation is suitable for separating:
A) Mixture of sand and salt
B) Mixture of alcohol and water
C) Mixture of nitrogen and oxygen
D) Mixture of oil and water
✅ Answer: B) Mixture of alcohol and water
- A) Incorrect: Sand + salt → sublimation/filtration.
- B) Correct: Different boiling points separate miscible liquids.
- C) Incorrect: Air separation uses fractional distillation of liquid air.
- D) Incorrect: Oil + water separate by separating funnel.
Q19. Which of the following is NOT a colloid?
A) Fog
B) Smoke
C) Sugar solution
D) Milk
✅ Answer: C) Sugar solution
- A) Incorrect: Fog is liquid in gas.
- B) Incorrect: Smoke is solid in gas.
- C) Correct: Sugar solution is a true solution.
- D) Incorrect: Milk is emulsion (colloid).
Q20. Which is NOT a physical method of separation?
A) Filtration
B) Chromatography
C) Distillation
D) Burning
✅ Answer: D) Burning
- A, B, C) Incorrect: All are physical separation methods.
- D) Correct: Burning is a chemical reaction.
Q21. Which of these is an element?
A) Water
B) Carbon
C) Air
D) Brass
✅ Answer: B) Carbon
- A) Incorrect: Water is compound.
- B) Correct: Carbon is an element.
- C, D) Incorrect: Mixtures.
Q22. Which property is common in mixtures?
A) Fixed composition
B) Components retain properties
C) New substance is formed
D) Uniform chemical formula
✅ Answer: B) Components retain properties
- A) Incorrect: Mixtures do not have fixed ratio.
- B) Correct: Components retain identity.
- C) Incorrect: No new substance.
- D) Incorrect: No fixed formula.
Q23. Which of the following can be separated by separating funnel?
A) Alcohol and water
B) Oil and water
C) Salt and water
D) Sugar and water
✅ Answer: B) Oil and water
- A) Incorrect: Miscible liquids → distillation.
- B) Correct: Immiscible liquids → separating funnel.
- C, D) Incorrect: Solids dissolved in water → evaporation/distillation.
Q24. Which of the following is a heterogeneous mixture?
A) Brass
B) Soil
C) Salt solution
D) Air
✅ Answer: B) Soil
- A) Incorrect: Brass is homogeneous.
- B) Correct: Soil is non-uniform.
- C, D) Incorrect: Both are homogeneous mixtures.
Q25. Which is the best method to separate different gases from air?
A) Chromatography
B) Filtration
C) Fractional distillation of liquid air
D) Evaporation
✅ Answer: C) Fractional distillation of liquid air
- A) Incorrect: Chromatography separates dyes.
- B) Incorrect: Filtration not applicable.
- C) Correct: Air is liquefied and separated by boiling points.
- D) Incorrect: Evaporation not suitable.
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