Class 9 Science NCERT MCQs Chapter 2 IS MATTER AROUND US PURE?

NCERT MCQs of Class 9 Science (Chemistry) Chapter 2 Is Matter Around Us Pure?

 1) Which of the following is a pure substance?

(a) Air
(b) Brass
(c) Water
(d) Soil
Answer: (c) Water
Explanation: Water is a pure substance because it has a fixed composition and chemical formula (H₂O).

2) What type of mixture is a solution of sugar in water?
(a) Homogeneous mixture
(b) Heterogeneous mixture
(c) Colloid
(d) Suspension
Answer: (a) Homogeneous mixture
Explanation: Sugar dissolves completely in water, forming a uniform mixture throughout.

3) Which of the following can be separated using a separating funnel?
(a) Salt and water
(b) Oil and water
(c) Alcohol and water
(d) Sugar and water
Answer: (b) Oil and water
Explanation: Oil and water are immiscible liquids and can be separated using a separating funnel.

4) What happens to the solubility of solids in water as temperature increases?
(a) It decreases
(b) It increases
(c) It remains unchanged
(d) It first increases and then decreases
Answer: (b) It increases
Explanation: Most solids dissolve better in hot water because heat provides energy to break bonds in the solid.

5) Which of the following is an example of a colloid?
(a) Salt solution
(b) Muddy water
(c) Milk
(d) Iron filings in sand
Answer: (c) Milk
Explanation: Milk is a colloidal solution where fat globules are dispersed in water.

6) The Tyndall effect is observed in which type of mixture?
(a) True solution
(b) Colloid
(c) Suspension
(d) Compound
Answer: (b) Colloid
Explanation: Colloids scatter light due to the larger size of dispersed particles, causing the Tyndall effect.

7) A mixture of sand and salt can be separated by
(a) Evaporation and condensation
(b) Filtration and evaporation
(c) Chromatography
(d) Sublimation
Answer: (b) Filtration and evaporation
Explanation: Sand is separated by filtration, and salt is recovered by evaporating the water.

8) Which separation technique is used to separate the colors in ink?
(a) Filtration
(b) Chromatography
(c) Sedimentation
(d) Sublimation
Answer: (b) Chromatography
Explanation: Chromatography is used to separate different components of a mixture based on their solubility.

9) Which of the following mixtures is heterogeneous?
(a) Sugar in water
(b) Air
(c) Blood
(d) Alcohol in water
Answer: (c) Blood
Explanation: Blood is heterogeneous as it contains different components that do not mix uniformly.

10) Which process is used to separate a soluble solid from a liquid?
(a) Filtration
(b) Sedimentation
(c) Evaporation
(d) Decantation
Answer: (c) Evaporation
Explanation: Evaporation removes the liquid, leaving the dissolved solid behind.

11) Which of the following statements about a suspension is correct?
(a) It is a homogeneous mixture
(b) The particles do not settle down
(c) It scatters light
(d) It is a pure substance
Answer: (c) It scatters light
Explanation: Suspensions contain large particles that scatter light and settle down over time.

12) Brass is an example of which type of mixture?
(a) Compound
(b) Homogeneous mixture
(c) Heterogeneous mixture
(d) Suspension
Answer: (b) Homogeneous mixture
Explanation: Brass is an alloy of copper and zinc, which forms a uniform mixture.

13) Which of the following methods is used to separate cream from milk?
(a) Chromatography
(b) Centrifugation
(c) Distillation
(d) Filtration
Answer: (b) Centrifugation
Explanation: Centrifugation separates substances based on density by spinning them at high speed.

14) Which property is used to separate a mixture by distillation?
(a) Difference in solubility
(b) Difference in boiling points
(c) Difference in particle size
(d) Difference in density
Answer: (b) Difference in boiling points
Explanation: Distillation works by heating a mixture so that one component evaporates before the other.

15) Which method is used to obtain pure water from seawater?
(a) Filtration
(b) Distillation
(c) Sedimentation
(d) Decantation
Answer: (b) Distillation
Explanation: Distillation removes impurities by evaporating water and then condensing it.

16) Which of the following is an example of a heterogeneous mixture?
(a) Saltwater
(b) Sugar solution
(c) Soil
(d) Alcohol in water
Answer: (c) Soil
Explanation: Soil contains different particles that do not mix uniformly.

17) The process of separating insoluble solids from a liquid using a filter paper is called
(a) Filtration
(b) Evaporation
(c) Sedimentation
(d) Crystallization
Answer: (a) Filtration
Explanation: Filtration allows the liquid to pass while retaining the solid.

18) The dispersed phase in a colloid is similar to a
(a) Suspension
(b) Solution
(c) Heterogeneous mixture
(d) Pure substance
Answer: (b) Solution
Explanation: In a colloid, the dispersed phase is finely divided but does not settle down.

19) The scattering of light in a colloidal solution is known as
(a) Brownian motion
(b) Tyndall effect
(c) Diffraction
(d) Reflection
Answer: (b) Tyndall effect
Explanation: The Tyndall effect occurs due to the scattering of light by colloidal particles.

20) What happens when a beam of light passes through a true solution?
(a) The beam is scattered
(b) The beam is reflected
(c) The beam is absorbed
(d) The beam passes through without scattering
Answer: (d) The beam passes through without scattering
Explanation: In a true solution, the particles are too small to scatter light.

21) The best method to separate ammonium chloride from sand is
(a) Sublimation
(b) Filtration
(c) Evaporation
(d) Crystallization
Answer: (a) Sublimation
Explanation: Ammonium chloride changes directly from solid to gas, leaving sand behind.

22) Which of the following is an example of a compound?
(a) Air
(b) Bronze
(c) Water
(d) Soil
Answer: (c) Water
Explanation: Water is a compound because it consists of two elements chemically combined in a fixed ratio.

23) What is the state of dispersed phase in an emulsion?
(a) Liquid
(b) Solid
(c) Gas
(d) None of these
Answer: (a) Liquid
Explanation: An emulsion consists of a liquid dispersed in another liquid (e.g., milk).

24) Which of the following is an example of an aerosol?
(a) Butter
(b) Paint
(c) Fog
(d) Cheese
Answer: (c) Fog
Explanation: Fog is an aerosol where water droplets are dispersed in air.

25) Which method is used to separate different pigments in a leaf extract?
(a) Filtration
(b) Chromatography
(c) Distillation
(d) Centrifugation
Answer: (b) Chromatography
Explanation: Chromatography separates substances based on their different solubilities.

26) Which of the following is a non-metal?
(a) Copper
(b) Sulfur
(c) Iron
(d) Aluminum
Answer: (b) Sulfur
Explanation: Sulfur is a non-metal with distinct physical and chemical properties.

27) Which technique is used to separate acetone from water?
(a) Filtration
(b) Distillation
(c) Sedimentation
(d) Crystallization
Answer: (b) Distillation
Explanation: Acetone and water have different boiling points, allowing separation by distillation.

28) In a true solution, the solute particles are
(a) Larger than solvent particles
(b) Uniformly distributed
(c) Visible under a microscope
(d) Separated by filtration
Answer: (b) Uniformly distributed
Explanation: A true solution is homogeneous, meaning solute particles are evenly spread.

29) The method used to separate immiscible liquids is
(a) Distillation
(b) Chromatography
(c) Separating funnel
(d) Evaporation
Answer: (c) Separating funnel
Explanation: A separating funnel helps separate two immiscible liquids based on their densities.

30) The Brownian motion in colloids is due to
(a) Gravity
(b) Temperature changes
(c) Collisions with dispersion medium particles
(d) Magnetic forces
Answer: (c) Collisions with dispersion medium particles
Explanation: Brownian motion occurs due to random collisions between colloidal particles and surrounding molecules.

31) Which of the following is a characteristic of a compound?
(a) It has variable composition
(b) Its properties are similar to its constituent elements
(c) It can be separated into elements by physical methods
(d) It has a fixed composition
Answer: (d) It has a fixed composition
Explanation: A compound consists of elements in a definite ratio and has unique properties.

32) The process of converting a solid directly into gas is called
(a) Evaporation
(b) Condensation
(c) Sublimation
(d) Distillation
Answer: (c) Sublimation
Explanation: Sublimation occurs in substances like ammonium chloride and camphor.

33) Which type of mixture can be separated using a separating funnel?
(a) Homogeneous
(b) Immiscible liquids
(c) Miscible liquids
(d) Colloids
Answer: (b) Immiscible liquids
Explanation: A separating funnel is used to separate liquids that do not mix, such as oil and water.

34) The dispersed phase in fog is
(a) Solid
(b) Liquid
(c) Gas
(d) Plasma
Answer: (b) Liquid
Explanation: Fog consists of tiny water droplets suspended in air.

35) Which technique is used to separate a solute from its solution by heating it?
(a) Filtration
(b) Crystallization
(c) Sublimation
(d) Sedimentation
Answer: (b) Crystallization
Explanation: Crystallization helps obtain pure solute from a solution by slow evaporation.

36) What is an alloy?
(a) A compound of two metals
(b) A pure element
(c) A homogeneous mixture of metals
(d) A heterogeneous mixture of metals
Answer: (c) A homogeneous mixture of metals
Explanation: Alloys are uniform mixtures of metals, like brass (copper + zinc).

37) The principle of chromatography is based on
(a) Difference in boiling points
(b) Difference in solubility
(c) Difference in densities
(d) Difference in magnetic properties
Answer: (b) Difference in solubility
Explanation: Chromatography separates substances based on their different solubilities in a solvent.

38) The process of removing the liquid from a solid-liquid mixture by heating is called
(a) Sedimentation
(b) Filtration
(c) Evaporation
(d) Crystallization
Answer: (c) Evaporation
Explanation: Evaporation removes the solvent, leaving the solute behind.

39) What type of mixture is smoke?
(a) Aerosol
(b) Suspension
(c) Solution
(d) Emulsion
Answer: (a) Aerosol
Explanation: Smoke consists of solid particles dispersed in a gas.

40) Why does milk appear white?
(a) Due to large fat particles
(b) Due to the Tyndall effect
(c) Due to reflection
(d) Due to Brownian motion
Answer: (b) Due to the Tyndall effect
Explanation: The Tyndall effect causes light to scatter, making milk appear white.

41) What is the dispersed phase in butter?
(a) Gas
(b) Liquid
(c) Solid
(d) None of these
Answer: (b) Liquid
Explanation: Butter is an emulsion where liquid fat is dispersed in water.

42) Which method is best for separating sodium chloride from its solution in water?
(a) Filtration
(b) Sublimation
(c) Evaporation
(d) Distillation
Answer: (c) Evaporation
Explanation: Evaporation removes water, leaving behind solid sodium chloride.

43) Which of the following is a colloidal solution?
(a) Sugar solution
(b) Paint
(c) Saltwater
(d) Copper sulfate solution
Answer: (b) Paint
Explanation: Paint is a colloid where solid pigments are dispersed in a liquid medium.

44) In which method does the solvent rise along the filter paper carrying solute with it?
(a) Chromatography
(b) Distillation
(c) Centrifugation
(d) Decantation
Answer: (a) Chromatography
Explanation: Chromatography separates substances based on solubility in a mobile phase.

45) What type of solution is vinegar?
(a) Suspension
(b) Colloid
(c) True solution
(d) Emulsion
Answer: (c) True solution
Explanation: Vinegar is a homogeneous mixture of acetic acid in water.

46) Which of the following is an example of a liquid-liquid colloidal system?
(a) Smoke
(b) Fog
(c) Emulsion
(d) Alloy
Answer: (c) Emulsion
Explanation: An emulsion consists of liquid droplets dispersed in another liquid.

47) What is the main criterion for separating a mixture by sedimentation?
(a) Difference in solubility
(b) Difference in particle size
(c) Difference in density
(d) Difference in boiling points
Answer: (c) Difference in density
Explanation: Heavier particles settle down, allowing separation.

48) The best method to separate iron filings from a mixture of sand and iron is
(a) Filtration
(b) Sublimation
(c) Magnetic separation
(d) Evaporation
Answer: (c) Magnetic separation
Explanation: Iron is magnetic and can be separated using a magnet.

49) What happens when a colloidal solution is left undisturbed for a long time?
(a) Particles settle down
(b) Particles remain suspended
(c) Solution becomes clear
(d) Particles dissolve completely
Answer: (b) Particles remain suspended
Explanation: Colloidal particles do not settle due to Brownian motion.

50) Why is water considered a universal solvent?
(a) It is colorless
(b) It dissolves most substances
(c) It has a low boiling point
(d) It does not react with other substances
Answer: (b) It dissolves most substances
Explanation: Water can dissolve a wide variety of solutes due to its polarity.

51) Which of the following statements about solutions is incorrect?
(a) They are homogeneous
(b) Their solute particles are visible under a microscope
(c) They cannot be separated by filtration
(d) They do not scatter light
Answer: (b) Their solute particles are visible under a microscope
Explanation: True solutions have solute particles too small to be seen under a microscope.

52) The method used to separate a mixture of salt and ammonium chloride is
(a) Distillation
(b) Sublimation
(c) Sedimentation
(d) Filtration
Answer: (b) Sublimation
Explanation: Ammonium chloride sublimes, while salt does not.

53) Which of the following is an example of an element?
(a) Bronze
(b) Air
(c) Oxygen
(d) Seawater
Answer: (c) Oxygen
Explanation: Oxygen is a pure element, while the others are mixtures.

54) Which of the following mixtures is separated by winnowing?
(a) Sand and iron
(b) Husk and grain
(c) Salt and water
(d) Sugar and sand
Answer: (b) Husk and grain
Explanation: Winnowing separates lighter husk from heavier grains using wind.

55) Which technique is best for separating different gases from air?
(a) Evaporation
(b) Filtration
(c) Fractional distillation
(d) Sedimentation
Answer: (c) Fractional distillation
Explanation: Air is separated into components based on boiling points.

56) What happens when a colloid is centrifuged?
(a) It dissolves completely
(b) Particles settle down
(c) It remains unchanged
(d) It evaporates
Answer: (b) Particles settle down
Explanation: Centrifugation forces heavier particles to settle.

57) Which of the following is an example of a gaseous solution?
(a) Smoke
(b) Fog
(c) Air
(d) Milk
Answer: (c) Air
Explanation: Air is a homogeneous mixture of gases.

58) Which technique is used to obtain pure crystals of salt from seawater?
(a) Chromatography
(b) Evaporation
(c) Filtration
(d) Centrifugation
Answer: (b) Evaporation
Explanation: Water evaporates, leaving behind salt crystals.

59) The Brownian motion of colloidal particles is due to
(a) Gravity
(b) Molecular collisions
(c) Light absorption
(d) Chemical reactions
Answer: (b) Molecular collisions

Explanation: A physical change is a change in the state or appearance of a substance without altering its chemical composition. When salt dissolves in water, no new substance is formed, and the process is reversible by evaporation, making it a physical change.

60) The property of metals to be drawn into wires is called
(a) Malleability
(b) Ductility
(c) Hardness
(d) Brittleness
Answer: (b) Ductility

Explanation: Distillation is a method used to separate a liquid from a solution based on differences in boiling points. In the case of seawater, water evaporates upon heating and is then condensed to obtain pure water, leaving the dissolved salts behind.