Chapter 2 : Is Matter Around Us Pure? (practice questions)

Purity of Substances Quiz

🧪 Purity of Substances Quiz! 🧪

Test your knowledge about this chapter 2 Is Matter Around Us Pure?. Select your answer and click "Submit Answer" to check if you're correct! ✅

1. Which of the following is a pure substance?

(a) Milk
(b) Sea water
(c) Distilled water
(d) Soil

2. Assertion: Milk is a pure substance.
Reason: Milk consists of water, fat, and proteins.

(a) Both Assertion and Reason are correct, and Reason is the correct explanation.
(b) Both Assertion and Reason are correct, but Reason is not the correct explanation.
(c) Assertion is incorrect, but Reason is correct.
(d) Both Assertion and Reason are incorrect.

3. Match the following substances with their purity status:

Column A
1. Gold (24K)
2. Air
3. Table Salt
4. Orange Juice

Column B
A. Homogeneous Mixture
B. Heterogeneous Mixture
C. Pure Substance
D. Solution

(a) 1-C, 2-A, 3-D, 4-B
(b) 1-B, 2-C, 3-A, 4-D
(c) 1-D, 2-B, 3-C, 4-A
(d) 1-A, 2-D, 3-B, 4-C

4. True or False: All mixtures are impure substances.

(a) True
(b) False

5. What is true about a mixture?

(a) It contains only one kind of pure substance.
(b) It contains more than one kind of pure substance.
(c) It contains only elements.
(d) It is always homogeneous.

6. Which of the following is a characteristic of a pure substance?

(a) It is a mixture of different substances.
(b) It has the same composition throughout.
(c) It can be separated into its components by physical processes.
(d) It consists of more than one element or compound.

7. Which of the following is an example of a mixture?

(a) Sodium chloride (NaCl)
(b) Distilled water
(c) Soft drink
(d) Pure gold

8. Which of the following is true about sugar?

(a) Sugar is a mixture of different substances.
(b) Sugar contains only one kind of pure substance and has the same composition throughout.
(c) Sugar can be separated into its components using physical methods.
(d) Sugar is made up of different chemical elements.

9. Which of the following is an example of a homogeneous mixture?

(a) Salt and iron filings
(b) Oil and water
(c) Copper sulphate solution in water
(d) Sand and salt

10. Which of the following is an example of a heterogeneous mixture?

(a) Sugar dissolved in water
(b) Copper sulphate solution
(c) Oil and water
(d) Salt dissolved in alcohol

11. Which of the following is a characteristic of a solution?

(a) The components are physically distinct and easy to separate.
(b) The components are evenly distributed, and the mixture is clear.
(c) The mixture forms layers that can be seen.
(d) The mixture is cloudy and opaque.

12. What is a colloidal solution?

(a) A solution where the solute is completely dissolved.
(b) A mixture where the particles are large and can be seen with the naked eye.
(c) A mixture where the solute particles are dispersed but not dissolved.
(d) A mixture where the solute and solvent form separate layers.

13. Which of the following is a characteristic of a suspension?

(a) The particles are uniformly distributed and do not settle over time.
(b) The particles are large, visible to the naked eye, and settle after some time.
(c) The mixture is clear and homogeneous.
(d) The particles are dissolved and cannot be seen.

14. Which of the following is an example of a solid-in-liquid solution?

(a) Air
(b) Tincture of iodine
(c) Lemonade
(d) Soda water

15. Which of the following is a property of a solution?

(a) The particles are visible to the naked eye.
(b) The particles scatter a beam of light passing through the solution.
(c) The solution is a heterogeneous mixture.
(d) The particles cannot be separated by filtration.

16. Assertion: Air is a solution of gases in gases.
Reason: Air contains oxygen (21%) and nitrogen (78%) in a homogeneous mixture.

(a) Both Assertion and Reason are correct, and Reason is the correct explanation.
(b) Both Assertion and Reason are correct, but Reason is not the correct explanation.
(c) Assertion is correct, but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.

17. Match the following solutions with their components:

Column A
1. Sugar in water
2. Air
3. Tincture of iodine
4. Soda water

Column B
A. Solid in liquid
B. Gas in gas
C. Solid in liquid
D. Gas in liquid

(a) 1-A, 2-B, 3-C, 4-D
(b) 1-B, 2-A, 3-D, 4-C
(c) 1-C, 2-B, 3-A, 4-D
(d) 1-D, 2-C, 3-A, 4-B

18. Which of the following is an example of a gas-in-liquid solution?

(a) Lemonade
(b) Soda water
(c) Salt in water
(d) Brass

19. Assertion: Brass is an alloy of copper and zinc.
Reason: Brass is a solid solution of copper and zinc.

(a) Both Assertion and Reason are correct, and Reason is the correct explanation.
(b) Both Assertion and Reason are correct, but Reason is not the correct explanation.
(c) Assertion is correct, but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.

20. Which of the following is true about the properties of solutions?

(a) The particles of a solution are larger than 1 nm in diameter.
(b) The particles of a solution scatter a beam of light.
(c) A solution is stable and the solute particles do not settle down.
(d) A solution is heterogeneous and can be separated by filtration.

21. Match the following solutions with their properties:

Column A
1. Brass
2. Soda water
3. Salt solution
4. Milk

Column B
A. Gas in liquid
B. Solid in liquid
C. Solid in solid
D. Colloidal solution

(a) 1-C, 2-A, 3-B, 4-D
(b) 1-B, 2-C, 3-D, 4-A
(c) 1-A, 2-B, 3-D, 4-C
(d) 1-D, 2-A, 3-C, 4-B

22. What is a saturated solution?

(a) A solution where no more solute can be dissolved at a given temperature.
(b) A solution that contains only a small amount of solute compared to the solvent.
(c) A solution where solute particles are completely dissolved and settled at the bottom.
(d) A solution where solute is present in a higher amount than the solvent.

23. Which of the following is true about a dilute solution?

(a) It contains a small amount of solute relative to the solvent.
(b) It contains a large amount of solute relative to the solvent.
(c) It is a type of saturated solution.
(d) It is a solution with the maximum possible solute dissolved in the solvent.

24. What happens when a saturated solution is cooled slowly?

(a) The solute may precipitate out of the solution.
(b) The solute remains completely dissolved in the solution.
(c) The solution becomes unsaturated.
(d) The solution becomes more concentrated.

25. The mass by mass percentage of a solution is given by:

(a) (Mass of solute / Mass of solvent) × 100
(a) (Mass of solute / Mass of solution) × 100
(a) (Volume of solute / Volume of solution) × 100
(a) (Volume of solute / Volume of solvent) × 100

26. Which of the following formulas represents volume by volume percentage?

(a) (Volume of solute / Volume of solution) × 100
(a) (Mass of solute / Mass of solution) × 100
(a) (Volume of solute / Volume of solvent) × 100
(a) (Mass of solute / Volume of solution) × 100

27. Assertion and Reason:

Assertion: A saturated solution contains as much solute as can dissolve in the solvent at a given temperature.
Reason: Solubility of a substance increases with a decrease in temperature.

(a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.

28. Match the following:

Column 1	Column 2
1. Brass	(a) Gas in gas solution
2. Soda Water	(b) Solid in solid solution
3. Air	(c) Liquid in liquid solution
4. Iodine in Alcohol	(d) Solid in liquid solution

(a) 1-b, 2-d, 3-a, 4-c
(b) 1-c, 2-d, 3-b, 4-a
(c) 1-d, 2-b, 3-c, 4-a
(d) 1-b, 2-c, 3-d, 4-a

29. Assertion and Reason:

Assertion: A solution is always homogeneous.
Reason: The solute particles in a solution are evenly distributed in the solvent.

30. Match the following: Solution Type

Column 1	Column 2
1. Tincture of Iodine	(a) Solid in liquid solution
2. Brass	(b) Gas in liquid solution
3. Air	(c) Solid in solid solution
4. Soda Water	(d) Liquid in liquid solution

(a) 1-d, 2-c, 3-b, 4-a
(b) 1-a, 2-c, 3-b, 4-d
(c) 1-c, 2-d, 3-a, 4-b
(d) 1-b, 2-c, 3-a, 4-d

31. Assertion and Reason:

Assertion: Suspension is a heterogeneous mixture where solute particles remain suspended in the liquid.
Reason: The particles in a suspension can be separated by filtration.

32. Match the following: Properties of Suspensions

Column 1	Column 2
1. Heterogeneous mixture	(a) Particles can be seen with the naked eye
2. Settling of particles	(b) Light is scattered by particles
3. Scatter light	(c) Particles settle down when undisturbed
4. Particles visible	(d) Particles do not dissolve in the medium

(a) 1-a, 2-c, 3-b, 4-d
(b) 1-d, 2-b, 3-c, 4-a
(c) 1-b, 2-a, 3-d, 4-c
(d) 1-c, 2-d, 3-a, 4-b

33. Assertion and Reason:

Assertion: In a suspension, the particles scatter light.
Reason: Suspension is a stable mixture in which the solute particles do not settle over time.

34. Match the following: Suspension Properties

Column 1	Column 2
1. Milk	(a) Solute particles settle over time
2. Muddy water	(b) Particles scatter light
3. Dust in air	(c) Solute particles can be seen with naked eye
4. Sand in water	(d) Heterogeneous mixture

(a) 1-d, 2-a, 3-b, 4-c
(b) 1-c, 2-b, 3-d, 4-a
(c) 1-b, 2-d, 3-a, 4-c
(d) 1-a, 2-c, 3-b, 4-d

35. Which of the following is NOT a characteristic of a suspension?

(a) The particles can be seen with the naked eye.
(b) The particles settle down when left undisturbed.
(c) The particles are uniformly distributed in the solution.
(d) The suspension scatters light.

36. Which of the following statements about a colloidal solution is FALSE?

(a) The particles of a colloid are too small to be seen with the naked eye.
(b) Colloidal particles can scatter a beam of light, creating the Tyndall effect.
(c) Colloidal solutions are homogeneous mixtures, and their components can be easily separated by filtration.
(d) Colloidal solutions do not settle when left undisturbed.

37. Assertion: Colloidal solutions can scatter light, demonstrating the Tyndall effect.
Reason: The particle size of colloidal solutions is large enough to scatter light.

(a) Both Assertion and Reason are correct, and the Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are correct, but the Reason is not the correct explanation of the Assertion.
(c) Assertion is correct, but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.

38. Match the following types of colloids with their examples:

Column A
1. Foam
2. Sol
3. Emulsion
4. Aerosol

Column B
A. Milk
B. Soap Foam
C. Paint
D. Fog

(a) 1-B, 2-C, 3-A, 4-D
(b) 1-D, 2-A, 3-C, 4-B
(c) 1-A, 2-B, 3-D, 4-C
(d) 1-C, 2-D, 3-B, 4-A

39. In the activity to separate the dye from ink, which component of the ink gets evaporated during heating?

(a) The ink itself
(b) The solvent (water)
(c) The dye
(d) Both the solvent and dye

40. Assertion: Ink is a mixture of water and dye.
Reason: The dye can be separated from ink using the method of evaporation.

41. Match the following methods of separation with their respective examples:

Column A
1. Filtration
2. Evaporation
3. Handpicking
4. Sieving

Column B
A. Separating sand from water
B. Separating salt from water
C. Removing larger particles from a mixture
D. Separating stones from rice

(a) 1-A, 2-B, 3-D, 4-C
(b) 1-B, 2-A, 3-C, 4-D
(c) 1-C, 2-D, 3-A, 4-B
(d) 1-D, 2-C, 3-B, 4-A

42. Which method can be used to separate a mixture of sand and water?

(a) Evaporation
(b) Filtration
(c) Centrifugation
(d) Chromatography

43. Assertion: Evaporation is used to separate solid dissolved in a liquid.
Reason: During evaporation, the liquid evaporates, leaving behind the solid solute.

44. Match the following separation techniques with their use:

Column A
1. Handpicking
2. Filtration
3. Evaporation
4. Centrifugation

Column B
A. Separating water from a salt solution
B. Separating heavier particles from liquid
C. Removing stones from rice
D. Separating sand from water

(a) 1-C, 2-D, 3-A, 4-B
(b) 1-A, 2-B, 3-D, 4-C
(c) 1-D, 2-A, 3-B, 4-C
(d) 1-B, 2-C, 3-A, 4-D

45. What is the principle used in the centrifugation method for separating cream from milk?

(a) The denser particles are forced to the bottom and the lighter particles stay at the top.
(b) The lighter particles are forced to the bottom and the denser particles stay at the top.
(c) The particles dissolve and form a homogeneous solution.
(d) The particles separate based on their solubility.

46. Assertion: Centrifugation is used to separate cream from milk.
Reason: In centrifugation, denser substances move towards the center, and lighter substances move away.

47. Match the following methods with their uses:

Column A
1. Centrifugation
2. Filtration
3. Evaporation
4. Sieving

Column B
A. Separating cream from milk
B. Separating solid particles from a liquid
C. Separating soluble solute from liquid
D. Separating particles of different sizes

(a) 1-A, 2-B, 3-C, 4-D
(b) 1-B, 2-A, 3-D, 4-C
(c) 1-C, 2-D, 3-A, 4-B
(d) 1-D, 2-C, 3-B, 4-A

48. Which of the following methods is commonly used to separate cream from milk in dairies?

(a) Filtration
(b) Distillation
(c) Centrifugation
(d) Evaporation

49. Assertion: The separation of cream from milk by centrifugation is a result of the difference in densities of cream and milk.
Reason: In centrifugation, the lighter substance is pushed to the center of the machine.

50. Match the following separation methods with their applications:

Column A
1. Centrifugation
2. Filtration
3. Distillation
4. Sieving

Column B
A. Separating solid particles from liquid
B. Separating cream from milk
C. Separating components based on boiling point
D. Separating components based on size

(a) 1-B, 2-A, 3-C, 4-D
(b) 1-A, 2-D, 3-B, 4-C
(c) 1-C, 2-A, 3-D, 4-B
(d) 1-D, 2-C, 3-A, 4-B

51. True or False: In centrifugation, the denser particles move towards the center of the spinning chamber.

(a) True
(b) False

52. Which method is used to separate a mixture of immiscible liquids like oil and water?

(a) Filtration
(b) Distillation
(c) Separating Funnel
(d) Evaporation

53. Assertion: Immiscible liquids like oil and water can be separated using a separating funnel.
Reason: Immiscible liquids form layers based on their densities when left undisturbed.

54. Match the following separation methods with their applications:

Column A
1. Separating Funnel
2. Centrifugation
3. Distillation
4. Filtration

Column B
A. Separating immiscible liquids like oil and water
B. Separating cream from milk
C. Separating based on boiling points
D. Separating solid from liquid

(a) 1-A, 2-B, 3-C, 4-D
(b) 1-B, 2-A, 3-D, 4-C
(c) 1-D, 2-C, 3-A, 4-B
(d) 1-A, 2-C, 3-D, 4-B

55. True or False: In a separating funnel, the heavier liquid settles at the top while the lighter liquid remains at the bottom.

(a) True
(b) False

56. Which method is used to separate a mixture of salt and camphor?

(a) Filtration
(b) Sublimation
(c) Centrifugation
(d) Distillation

57. Assertion: Camphor can be separated from a mixture of salt and camphor by sublimation.
Reason: Sublimation is the process where a solid directly changes into gas without becoming a liquid.

58. Match the following methods of separation with their suitable applications:

Column A
1. Sublimation
2. Filtration
3. Centrifugation
4. Distillation

Column B
A. Separating a solid from a liquid
B. Separating salt and camphor
C. Separating cream from milk
D. Separating liquids based on boiling points

(a) 1-B, 2-A, 3-C, 4-D
(b) 1-C, 2-A, 3-B, 4-D
(c) 1-A, 2-B, 3-C, 4-D
(d) 1-D, 2-B, 3-A, 4-C

59. True or False: Camphor is separated from salt using the process of filtration.

(a) True
(b) False

60. What does chromatography help separate in a dye?

(a) Solvents from the dye
(b) Different colors present in the dye
(c) Solid particles from the liquid
(d) Water molecules from the dye

61. Assertion: Chromatography is used to separate different colors in a dye.
Reason: Chromatography separates components based on their solubility in the solvent.

62. Match the following methods with their suitable applications:

Column A
1. Chromatography
2. Filtration
3. Evaporation
4. Sublimation

Column B
A. To separate colors in a dye
B. To separate a solid from a liquid
C. To separate volatile substances
D. To separate water from ink

(a) 1-A, 2-B, 3-D, 4-C
(b) 1-B, 2-C, 3-A, 4-D
(c) 1-A, 2-D, 3-B, 4-C
(d) 1-C, 2-A, 3-B, 4-D

63. True or False: In chromatography, the component that is more soluble in the solvent will move slower on the filter paper.

(a) True
(b) False

64. Which of the following methods is used to separate a mixture of salt and camphor?

(a) Filtration
(b) Centrifugation
(c) Sublimation
(d) Distillation

65. Assertion: Sublimation can be used to separate a mixture of naphthalene and sand.
Reason: Naphthalene sublimes when heated, while sand does not sublime.

66. Match the following separation techniques with their appropriate uses:

Column A
1. Filtration
2. Centrifugation
3. Sublimation
4. Chromatography

Column B
A. To separate components based on solubility
B. To separate a solid from a liquid
C. To separate lighter substances from heavier ones
D. To separate a sublimable substance from non-sublimable impurities

(a) 1-B, 2-C, 3-D, 4-A
(b) 1-A, 2-B, 3-C, 4-D
(c) 1-C, 2-A, 3-B, 4-D
(d) 1-B, 2-A, 3-D, 4-C

67. True or False: The separation of oil and water using a separating funnel works because the two liquids are immiscible and have different densities.

(a) True
(b) False

68. Which of the following methods is used to separate a mixture of acetone and water?

(a) Filtration
(b) Distillation
(c) Centrifugation
(d) Chromatography

69. Assertion: Distillation can be used to separate two miscible liquids that boil without decomposition.
Reason: Distillation works because the components of the mixture have a significant difference in their boiling points.

70. Match the following methods of separation with their appropriate uses:

Column A
1. Distillation
2. Fractional Distillation
3. Filtration
4. Chromatography

Column B
A. To separate miscible liquids with different boiling points
B. To separate components based on particle size
C. To separate components based on solubility
D. To separate miscible liquids with very close boiling points

(a) 1-A, 2-D, 3-B, 4-C
(b) 1-B, 2-D, 3-A, 4-C
(c) 1-C, 2-A, 3-B, 4-D
(d) 1-A, 2-B, 3-D, 4-C

71. True or False: Fractional distillation is used when the difference in boiling points of two miscible liquids is greater than 25°C.

(a) True
(b) False

72. Which method is used to obtain different gases from air?

(a) Filtration
(b) Chromatography
(c) Fractional distillation
(d) Centrifugation

73. Assertion: Air can be separated into its components by fractional distillation.
Reason: Different gases in air have different boiling points, which allows them to be separated through fractional distillation.

74. Match the following gases with their approximate boiling points:

Column A
1. Oxygen
2. Nitrogen
3. Argon
4. Carbon dioxide

Column B
A. -195.8°C
B. -183°C
C. -78.5°C
D. -196°C

(a) 1-B, 2-D, 3-A, 4-C
(b) 1-D, 2-A, 3-B, 4-C
(c) 1-A, 2-B, 3-C, 4-D
(d) 1-C, 2-A, 3-B, 4-D

75. True or False: Oxygen forms a liquid before nitrogen when air is cooled in the fractional distillation process.

(a) True
(b) False

76. What is the process used to obtain pure copper sulfate from an impure sample?

(a) Distillation
(b) Filtration
(c) Crystallization
(d) Centrifugation

77. Assertion: Crystallization is a better method for purifying solids compared to simple evaporation.
Reason: Some solids, like sugar, may decompose or get charred on heating, and crystallization helps avoid contamination from dissolved impurities.

78. Match the following processes with their respective applications:

Column A
1. Crystallization
2. Filtration
3. Distillation
4. Centrifugation

Column B
A. Purification of drinking water
B. Purification of impure copper sulfate
C. Separation of immiscible liquids
D. Separation of suspended solids from liquids

(a) 1-B, 2-D, 3-A, 4-C
(b) 1-A, 2-B, 3-C, 4-D
(c) 1-B, 2-C, 3-D, 4-A
(d) 1-A, 2-D, 3-B, 4-C

79. True or False: Crystallization can help remove impurities in solids that may remain dissolved even after filtration.

(a) True
(b) False

80. The process used to purify impure copper sulfate and obtain its crystals is called __________.

(a) Filtration
(b) Evaporation
(c) Crystallization
(d) Distillation

81. Which of the following is an example of a chemical change?

(a) Melting of ice
(b) Dissolving salt in water
(c) Burning of a candle
(d) Boiling of water

82. Assertion: A physical change does not result in a change in the chemical composition of a substance.
Reason: In a chemical change, new substances are formed with different chemical properties.

83. True or False: The burning of a candle involves both physical and chemical changes.

(a) True
(b) False

84. __________ is an example of a chemical change where the substance reacts with oxygen to form new products.

(a) Melting
(b) Freezing
(c) Burning
(d) Condensation

85. Match the following examples with the correct type of change:

Column A
1. Melting of ice
2. Burning of paper
3. Dissolving sugar in water
4. Rusting of iron

Column B
A. Chemical change
B. Physical change

(a) 1-B, 2-A, 3-B, 4-A
(b) 1-A, 2-B, 3-A, 4-B
(c) 1-B, 2-B, 3-A, 4-A
(d) 1-A, 2-A, 3-B, 4-B

86. Which of the following is an example of a chemical reaction?

(a) Freezing of water
(b) Melting of butter
(c) Heating sugar to caramelize it
(d) Dissolving salt in water

87. Assertion: A chemical change is always irreversible.
Reason: In a chemical change, new products with new properties are formed.

88. True or False: Burning of wood in a fireplace is a physical change.

(a) True
(b) False

89. The process of a substance reacting with oxygen to produce heat and light is known as __________.

90. Match the following changes with the type of change:

Column A
1. Dissolving sugar in tea
2. Burning of paper
3. Freezing water
4. Rusting of iron

Column B
A. Chemical change
B. Physical change

(a) 1-B, 2-A, 3-B, 4-A
(b) 1-A, 2-B, 3-A, 4-B
(c) 1-B, 2-B, 3-A, 4-A
(d) 1-A, 2-A, 3-B, 4-B

91. Which of the following is an example of a metal?

(a) Hydrogen
(b) Chlorine
(c) Copper
(d) Iodine

92. True or False: Non-metals are good conductors of electricity.

(a) True
(b) False

93. Elements with properties intermediate between metals and non-metals are called __________.

(a) Metalloids
(b) Alkali metals
(c) Noble gases
(d) Non-metals

94. Match the following properties with their respective categories of elements:

Column A
1. Good conductors of heat and electricity
2. Dull and poor conductors
3. Can be hammered into thin sheets
4. Liquid at room temperature

Column B
A. Non-metals
B. Metals
C. Metalloids

(a) 1-B, 2-A, 3-B, 4-C
(b) 1-A, 2-B, 3-C, 4-B
(c) 1-B, 2-C, 3-A, 4-B
(d) 1-A, 2-B, 3-B, 4-C

95. Name two elements that are considered metalloids.

(a) Boron and Silicon
(b) Iron and Copper
(c) Oxygen and Nitrogen
(d) Sodium and Potassium

96. What is a compound?

(a) A substance made up of two or more different elements chemically bonded together.
(b) A mixture of different elements that are not chemically bonded.
(c) A single element in a pure form.
(d) A substance made of atoms that cannot combine with others.

97. Which of the following is a property of compounds?

(a) Compounds can be separated by physical methods.
(b) The properties of compounds are the same as the elements that form them.
(c) Compounds have fixed ratios of elements.
(d) Compounds are mixtures of elements.

98. True or False: Compounds can be separated by physical methods.

(a) True
(b) False

99. Match the following compounds with their elements:

Column A
1. Water
2. Sodium chloride (NaCl)
3. Carbon dioxide
4. Ammonia

Column B
A. Hydrogen and oxygen
B. Sodium and chlorine
C. Carbon and oxygen
D. Nitrogen and hydrogen

(a) 1-A, 2-B, 3-C, 4-D
(b) 1-B, 2-C, 3-D, 4-A
(c) 1-C, 2-A, 3-D, 4-B
(d) 1-D, 2-A, 3-B, 4-C

100. A chemical bond that forms between two atoms when they share electrons is called a __________ bond.

(a) Ionic bond
(b) Metallic bond
(c) Covalent bond
(d) Hydrogen bond

101. How many naturally occurring elements are there?

(a) more than 100
(b) 92
(c) 105
(d) 120

102. Assertion: The majority of elements are solid at room temperature.

Reason: Elements that are solid have a fixed shape and volume at room temperature.

(a) Both Assertion and Reason are correct, and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) Assertion is correct, but Reason is incorrect.
(d) Assertion is incorrect, but Reason is correct.

103. Match the elements with their physical state at room temperature:

Column A
1. Mercury
2. Bromine
3. Gallium
4. Cesium

Column B
A. Solid
B. Liquid
C. Gas
D. Becomes liquid slightly above room temperature

(a) 1-B, 2-B, 3-D, 4-D
(b) 1-B, 2-C, 3-A, 4-D
(c) 1-A, 2-B, 3-D, 4-A
(d) 1-D, 2-A, 3-B, 4-C

104. Which two elements are liquid at room temperature?

(a) Gallium and Cesium
(b) Mercury and Bromine
(c) Sodium and Potassium
(d) Hydrogen and Oxygen

105. What is a compound?

(a) A substance composed of a single element.
(b) A substance composed of two or more elements chemically combined in a fixed proportion.
(c) A substance composed of two or more elements physically combined in any proportion.
(d) A mixture of different substances.

106. Assertion: The product obtained from the reaction of iron filings and sulphur powder after heating strongly is a compound.

Reason: A compound has different properties from the elements it is made from, and its composition is the same throughout.

107. Match the following with their correct descriptions:

Column A
1. Iron filings and sulphur powder (not heated)
2. Iron filings and sulphur powder (heated strongly)
3. Iron filings and sulphur powder after adding dilute sulphuric acid
4. Product formed after heating strongly

Column B
A. Mixture of two elements
B. Compound with different properties from its constituents
C. Gas with rotten egg smell
D. Hydrogen gas released

(a) 1-A, 2-B, 3-D, 4-C
(b) 1-A, 2-C, 3-D, 4-B
(c) 1-B, 2-A, 3-C, 4-D
(d) 1-C, 2-B, 3-D, 4-A

108. What type of change occurs when iron filings and sulphur are mixed but not heated?

(a) Physical change
(b) Chemical change
(c) Both physical and chemical change
(d) No change

109. Which of the following properties is true for a compound?

(a) A compound is made up of two or more elements chemically combined in fixed proportions.
(b) A compound retains the properties of the individual elements it is made from.
(c) The properties of a compound are always the same as the properties of its constituent elements.
(d) A compound can be easily separated into its components by physical methods.

110. Assertion: The reaction between iron and sulphur to form iron sulphide is a chemical change.

Reason: Chemical changes result in the formation of new substances with different properties from the original substances.

111. Which of the following statements is correct about the differences between an element and a compound?

(a) An element consists of only one type of atom, while a compound consists of two or more different atoms chemically bonded.
(b) A compound is a mixture of elements that are not chemically bonded.
(c) Elements cannot form compounds under any circumstances.
(d) A compound can consist of only one type of atom.

112. Match the following chemical changes with their products:

Column A
1. Heating iron filings and sulphur
2. Burning of hydrogen gas
3. Rusting of iron
4. Heating copper carbonate

Column B
A. Copper oxide and carbon dioxide
B. Hydrogen sulphide gas
C. Water and energy
D. Iron sulphide (FeS)

(a) 1-D, 2-C, 3-B, 4-A
(b) 1-D, 2-B, 3-C, 4-A
(c) 1-A, 2-B, 3-D, 4-C
(d) 1-C, 2-A, 3-D, 4-B

113. Which of the following is true about mixtures and compounds?

(a) Mixtures always have a fixed composition, while compounds have variable composition.
(b) The properties of a mixture are similar to those of its constituent substances, while a compound has entirely different properties.
(c) Mixtures can be separated by chemical methods, whereas compounds can be separated by physical methods.
(d) Mixtures are always formed by chemical reactions, while compounds are formed by physical methods.

114. Assertion: Mixtures can be separated by physical methods.

Reason: The constituents of a mixture retain their individual properties and can be separated easily without any chemical change.

115. Match the following features of mixtures and compounds:

Column A
1. Mixture
2. Compound
3. Separation method
4. Composition

Column B
A. Can be separated by physical methods
B. Has a fixed composition
C. Components retain their properties
D. Formed by chemical reactions

(a) 1-A, 2-B, 3-C, 4-D
(b) 1-C, 2-D, 3-A, 4-B
(c) 1-A, 2-C, 3-B, 4-D
(d) 1-D, 2-B, 3-C, 4-A

Chapter 2 : Is Matter Around Us Pure? (practice questions)

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Chapter 2 : Is Matter Around Us Pure? (practice questions)

🧪 Purity of Substances Quiz! 🧪

Ranjan Das

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