Class 9th Science Is matter around us pure Practice Questions

Section A – Multiple Choice Questions (MCQs) [Q.1–20]

1. Which of the following is a pure substance?
   a) Milk
   b) Brass
   c) Water
   d) Air
2. Brass is an example of:
   a) Compound
   b) Homogeneous mixture
   c) Heterogeneous mixture
   d) Pure substance
3. Air is an example of a:
   a) Compound
   b) Mixture
   c) Pure substance
   d) Colloid
4. Which technique is used to separate salt from seawater?
   a) Evaporation
   b) Filtration
   c) Sedimentation
   d) Sublimation
5. Which of the following is not a heterogeneous mixture?
   a) Sand and water
   b) Oil and water
   c) Sugar solution
   d) Soil
6. Which among the following is a compound?
   a) Brass
   b) Vinegar
   c) Air
   d) Steel
7. Which separation technique is used for separating camphor from salt?
   a) Distillation
   b) Evaporation
   c) Sublimation
   d) Filtration
8. A mixture of salt and ammonium chloride can be separated by:
   a) Filtration
   b) Evaporation
   c) Sublimation
   d) Decantation
9. Which of the following is a homogeneous mixture?
   a) Oil in water
   b) Soil
   c) Air
   d) Sand and water
10. The Tyndall effect is shown by:
    a) True solutions
    b) Colloids
    c) Compounds
    d) Suspensions
11. Which of the following is a colloid?
    a) Salt solution
    b) Blood
    c) Sand in water
    d) Brass
12. Vinegar is a solution of:
    a) Acetic acid in water
    b) Citric acid in alcohol
    c) Acetic acid in alcohol
    d) Citric acid in water
13. A solution which cannot dissolve more solute at a given temperature is called:
    a) Saturated solution
    b) Supersaturated solution
    c) Unsaturated solution
    d) Dilute solution
14. The scattering of light by colloidal particles is called:
    a) Brownian motion
    b) Diffusion
    c) Tyndall effect
    d) Reflection
15. Alloy is a:
    a) Heterogeneous mixture
    b) Compound
    c) Homogeneous mixture
    d) Element
16. Which method is used to separate dyes in black ink?
    a) Distillation
    b) Filtration
    c) Chromatography
    d) Evaporation
17. Which of the following is not a colloid?
    a) Milk
    b) Smoke
    c) Brass
    d) Fog
18. Which separation technique is used to obtain pure water from seawater?
    a) Filtration
    b) Sedimentation
    c) Distillation
    d) Decantation
19. Mixtures are formed by:
    a) Chemical reaction
    b) Physical process
    c) Both (a) and (b)
    d) None
20. Which of the following is a heterogeneous mixture?
    a) Salt solution
    b) Sugar solution
    c) Soil
    d) Air

Section B – True/False [Q.21–30]

21. A mixture has variable composition.
22. Pure substances are always elements.
23. The components of a mixture can be separated by physical methods.
24. Blood is a colloidal solution.
25. Alloys are homogeneous mixtures.
26. Distillation is used to separate immiscible liquids.
27. Milk is a suspension.
28. Air is always a heterogeneous mixture.
29. Saturated solution contains maximum solute at given temperature.
30. Filtration can be used to separate a dissolved solid from a liquid.

Section C – Fill in the Blanks [Q.31–40]

31. The process of separating cream from milk is called __________.
32. The colloidal solution of liquid in gas is called __________.
33. The scattering of light by colloids is known as __________.
34. Brass is an alloy of __________ and __________.
35. The mixture of mud and water can be separated by __________.
36. __________ method is used to separate salt from its solution in water.
37. A true solution is __________ at the microscopic level.
38. Fog is a colloidal solution of __________ in __________.
39. __________ is used to separate components of petroleum.
40. In a __________ solution, the solute is present in excess of its solubility.

Section D – Assertion & Reason [Q.41–50]

41. Assertion: Mixtures can be separated by physical methods.
    Reason: Components of mixtures retain their properties.
42. Assertion: Colloids show Tyndall effect.
    Reason: Colloidal particles are large enough to scatter light.
43. Assertion: Solutions are always homogeneous.
    Reason: Solute and solvent particles are uniformly distributed.
44. Assertion: Air is a compound.
    Reason: Air has a fixed composition of gases.
45. Assertion: Salt is obtained from seawater by evaporation.
    Reason: Water evaporates leaving salt behind.
46. Assertion: Chromatography is used for separation of dyes.
    Reason: Different dyes have different solubility in solvent.
47. Assertion: Alloys are pure substances.
    Reason: Alloys are formed by mixing metals physically.
48. Assertion: Milk is a colloid.
    Reason: Milk has fat particles dispersed in water.
49. Assertion: Distillation can separate alcohol and water.
    Reason: Alcohol and water have different boiling points.
50. Assertion: Mixtures are formed by physical processes.
    Reason: Mixtures always have fixed composition.

Section E – Very Short Answer (1 Mark Each) [Q.51–60]

51. Define pure substance.
52. Give one example of a homogeneous mixture.
53. Name the separation technique used to separate sand and salt.
54. State one property of suspension.
55. What is the composition of steel?
56. Define saturated solution.
57. Write one example of a colloid.
58. Name the method used to separate oil and water.
59. Which method is used to obtain alcohol from water?
60. What is the solute and solvent in sugar solution?

Section F – Short Answer (2 Marks Each) [Q.61–70]

61. Differentiate between homogeneous and heterogeneous mixtures.
62. Why is air considered a mixture?
63. Give one method to separate ammonium chloride and salt.
64. Why is alloy considered a mixture and not a compound?
65. What is chromatography? Give one application.
66. State two properties of colloids.
67. Differentiate between solution and suspension.
68. Why does salt dissolve in water?
69. Explain the process of distillation.
70. Give two examples of heterogeneous mixtures.

Section G – Short Answer (3 Marks Each) [Q.71–80]

71. Explain true solution, colloid, and suspension with examples.
72. Give differences between compound and mixture.
73. What is the role of centrifugation in separation?
74. Define miscible and immiscible liquids with examples.
75. Explain Brownian movement with respect to colloids.
76. Why is water a universal solvent?
77. Describe fractional distillation with one example.
78. Why can a mixture have variable composition?
79. Explain saturated, unsaturated, and supersaturated solutions.
80. How will you prove that air is a mixture?

Section H – Long Answer (4–5 Marks Each) [Q.81–90]

81. Describe various methods of separation of mixtures with examples.
82. Explain differences between elements, compounds, and mixtures.
83. Write properties of colloids with suitable examples.
84. Explain the process of crystallization with one example.
85. Compare suspension, colloid, and solution in tabular form.
86. Explain fractional distillation of air.
87. How will you separate a mixture of salt, sand, and ammonium chloride?
88. Discuss properties of a pure substance.
89. What are alloys? Write examples and uses.
90. Write an experiment to show Tyndall effect in colloids.

Section I – Case Study Based [Q.91–100]

Case Study 1 (Q.91–95):
A student prepares a mixture of salt, sand, and water in a beaker. He wants to separate each component.

91. Which method is used to remove sand?
92. Which method is used to obtain salt from solution?
93. Which property allows sand to be separated by filtration?
94. Write the steps to separate all three components.
95. Is the final salt obtained a pure substance or a mixture?

Case Study 2 (Q.96–100):
A bottle of milk is left outside in summer and cream is separated in the laboratory.

96. Which method is used to separate cream from milk?
97. Is milk a solution, suspension, or colloid?
98. Which effect can prove milk is a colloid?
99. Name another separation technique used in dairy industry.
100. State one difference between true solution and milk as a colloid.