Important MCQs on Pure Substances, Mixtures, and Solutions for CBSE Class-9 Science Chapter-2
1. What is a pure substance?
A) A mixture of different substances
B) A substance made up of only one type of
particle
C) A substance that changes colour
D) A mixture with uniform composition
Answer: B) A substance made up of only one
type of particle
Explanation: A pure substance consists of only
one type of atom or molecule, not a mixture of different substances.
2. Which of the following is a homogeneous
mixture?
A) Sand and salt
B) Oil and water
C) Lemonade
D) Cereal in milk
Answer: C) Lemonade
Explanation: A homogeneous mixture has a
uniform composition throughout. Lemonade, with sugar dissolved evenly in water,
is homogeneous.
3. Which one of these is an example of a
colloid?
A) Salt water
B) Sand in water
C) Milk
D) Ice cubes in soda
Answer: C) Milk
Explanation: Milk is a colloid because it has
tiny particles dispersed throughout that scatter light, making it appear
cloudy.
4. What happens to the particles in a
suspension when left undisturbed?
A) They dissolve completely
B) They settle down
C) They become a solution
D) They scatter light
Answer: B) They settle down
Explanation: In a suspension, particles are
large enough to settle at the bottom over time.
5. What is the dispersed phase in a colloid?
A) The substance in which particles are
dispersed
B) The particles that are dispersed
C) The solution that dissolves the particles
D) The solvent used in the colloid
Answer: B) The particles that are dispersed
Explanation: In a colloid, the dispersed phase
refers to the small particles that are distributed throughout the dispersion
medium.
6. Which method would you use to separate sand
from water?
A) Filtration
B) Evaporation
C) Distillation
D) Chromatography
Answer: A) Filtration
Explanation: Sand can be separated from water
using filtration, which allows the water to pass through while the sand is
trapped.
7. What type of mixture is formed when you
dissolve sugar in water?
A) Suspension
B) Colloid
C) Solution
D) Heterogeneous mixture
Answer: C) Solution
Explanation: A solution is formed when sugar
dissolves in water, creating a homogeneous mixture.
8. Which one of the following is a compound?
A) Air
B) Brass
C) Salt
D) Steel
Answer: C) Salt
Explanation: Salt (sodium chloride) is a
compound made from sodium and chlorine elements chemically combined.
9. What is the main difference between a
solution and a colloid?
A) Particle size
B) Solubility
C) Colour
D) Density
Answer: A) Particle size
Explanation: Solutions have particles smaller
than 1 nanometre and are homogeneous, while colloids have larger particles that
scatter light but are still not visible to the naked eye.
10. Which of these is an example of a
heterogeneous mixture?
A) Air
B) Orange juice with pulp
C) Sugar water
D) Vinegar
Answer: B) Orange juice with pulp
Explanation: Orange juice with pulp is
heterogeneous because the pulp and juice are visibly different components.
11. Which technique is used to separate a
solid from a liquid in a mixture?
A) Distillation
B) Filtration
C) Chromatography
D) Centrifugation
Answer: B) Filtration
Explanation: Filtration is used to separate
solids from liquids by passing the mixture through a filter that captures the
solid.
12. What is the role of a solvent in a
solution?
A) It dissolves the solute
B) It reacts with the solute
C) It adds colour to the solution
D) It evaporates from the solution
Answer: A) It dissolves the solute
Explanation: The solvent is the component of a
solution that dissolves the solute.
13. Which of the following is a property of
colloids?
A) They settle out on standing
B) They do not scatter light
C) They can be separated by filtration
D) They scatter light (Tyndall effect)
Answer: D) They scatter light (Tyndall effect)
Explanation: Colloids scatter light, which is
known as the Tyndall effect, making their path visible in a beam of light.
14. What is the effect of temperature on the
solubility of most salts?
A) Solubility decreases with temperature
B) Solubility remains constant
C) Solubility increases with temperature
D) Solubility first increases then decreases
Answer: C) Solubility increases with
temperature
Explanation: For most salts, their solubility
in water increases as the temperature rises.
15. Which mixture can be separated by
evaporation?
A) Sand and salt
B) Salt and water
C) Iron filings and sulphur
D) Oil and vinegar
Answer: B) Salt and water
Explanation: Salt can be separated from water
by evaporating the water, leaving the salt behind.
16. What is an example of a gas in a gas
solution?
A) Soda water
B) Air
C) Saltwater
D) Milk
Answer: B) Air
Explanation: Air is a homogeneous mixture of
gases, mainly nitrogen and oxygen.
17. Which process would best separate oil from
water?
A) Filtration
B) Distillation
C) Centrifugation
D) Separating funnel
Answer: D) Separating funnel
Explanation: A separating funnel is used to
separate immiscible liquids like oil and water.
18. What is the mass by mass percentage of a
solution with 10 g of salt in 90 g of water?
A) 10%
B) 20%
C) 9%
D) 10.5%
Answer: A) 10%
Explanation: The mass percentage is calculated
by (mass of solute / mass of solution) × 100 = (10 / (10 + 90)) × 100 = 10%.
19. What type of mixture is ketchup?
A) Solution
B) Suspension
C) Colloid
D) Pure substance
Answer: C) Colloid
Explanation: Ketchup is a colloid because it
has particles suspended throughout, which can scatter light.
20. Which substance would be best separated
using a magnet?
A) Salt and sugar
B) Iron filings and sand
C) Sand and salt
D) Milk and water
Answer: B) Iron filings and sand
Explanation: Iron filings can be separated
from sand using a magnet because iron is magnetic, but sand is not.
21. What happens when a saturated solution is
cooled?
A) More solute dissolves
B) Solute particles settle out
C) Solute dissolves further
D) Solution becomes unsaturated
Answer: B) Solute particles settle out
Explanation: As a saturated solution cools,
some solute may no longer be soluble and can settle out.
22. Which of the following mixtures is an
example of a solid in liquid solution?
A) Air
B) Saltwater
C) Milk
D) Oil and water
Answer: B) Saltwater
Explanation: Saltwater is a solution where the
solid salt is dissolved in the liquid water.
23. Which of these is a characteristic of a
solution?
A) The particles settle out
B) The particles can be seen with the naked
eye
C) The solution is always clear
D) The solute cannot be separated by
filtration
Answer: D) The solute cannot be separated by
filtration
Explanation: In a solution, the solute
particles are so small they pass through filters and cannot be separated by
filtration.
24. Which mixture would you use a centrifuge
to separate?
A) Salt and water
B) Sand and water
C) Cream and milk
D) Iron filings and sulphur
Answer: C) Cream and milk
Explanation: A centrifuge separates substances
based on density. It can be used to separate cream from milk.
25. Which of these techniques separates
components based on their solubility?
A) Filtration
B) Distillation
C) Chromatography
D) Centrifugation
Answer: C) Chromatography
Explanation: Chromatography separates
components based on their differing solubilities in a particular solvent.
26. What is the primary characteristic of a
suspension?
A) Homogeneous mixture
B) Settles out over time
C) Does not scatter light
D) Uniform composition
Answer: B) Settles out over time
Explanation: Suspensions have large particles
that settle out over time when left undisturbed.
27. How would you separate a mixture of salt
and sand?
A) Boil the mixture
B) Use a magnet
C) Filtration and evaporation
D) Use a separating funnel
Answer: C) Filtration and evaporation
Explanation: Filtration separates sand from
saltwater, and evaporation can then be used to get the salt from the saltwater.
28. Which property is used to separate
components of a mixture in chromatography?
A) Density
B) Particle size
C) Solubility
D) Magnetic property
Answer: C) Solubility
Explanation: Chromatography separates
components based on their different solubilities and affinities for the
stationary and mobile phases.
29. What type of mixture is cereal in milk?
A) Solution
B) Colloid
C) Suspension
D) Homogeneous mixture
Answer: C) Suspension
Explanation: Cereal in milk is a suspension
because the cereal particles do not dissolve and can be seen.
30. What process is used to separate a
dissolved solid from a solution?
A) Filtration
B) Distillation
C) Chromatography
D) Centrifugation
Answer: B) Distillation
Explanation: Distillation is used to separate dissolved solids from a solution based on different boiling points.
31. What is the function of a separating
funnel?
A) To dissolve solids
B) To separate immiscible liquids
C) To filter solid particles
D) To evaporate liquids
Answer: B) To separate immiscible liquids
Explanation: A separating funnel is used to
separate liquids that do not mix, like oil and water.
32. What is the main feature of a mixture?
A) Uniform composition
B) Consists of only one substance
C) Physical combination of substances
D) Chemical bonding of elements
Answer: C) Physical combination of substances
Explanation: A mixture is a physical
combination of two or more substances that retain their individual properties.
33. Which method is used to separate an
insoluble solid from a liquid?
A) Distillation
B) Filtration
C) Evaporation
D) Centrifugation
Answer: B) Filtration
Explanation: Filtration separates insoluble
solids from liquids by passing the mixture through a filter.
34. What type of mixture is mayonnaise?
A) Solution
B) Suspension
C) Colloid
D) Compound
Answer: C) Colloid
Explanation: Mayonnaise is a colloid because
it contains dispersed fat droplets in a continuous phase of vinegar or lemon
juice.
35. What is the key characteristic of a
solution?
A) Particles can be seen with the naked eye
B) Components are not uniformly mixed
C) It has a uniform composition throughout
D) The solute settles out over time
Answer: C) It has a uniform composition
throughout
Explanation: Solutions have a uniform
composition throughout, with the solute completely dissolved in the solvent.
36. What would be the best method to separate
a mixture of sugar and water?
A) Filtration
B) Centrifugation
C) Evaporation
D) Chromatography
Answer: C) Evaporation
Explanation: Evaporation is used to separate
sugar from water by evaporating the water, leaving the sugar behind.
37. What is an example of a solid in solid
solution?
A) Alloy
B) Saltwater
C) Air
D) Milk
Answer: A) Alloy
Explanation: An alloy, such as bronze or
steel, is a solid solution where different metals are mixed together.
38. How can you test if a solution is
unsaturated?
A) Add more solute and observe if it dissolves
B) Measure its boiling point
C) Check its colour
D) Observe if it separates into layers
Answer: A) Add more solute and observe if it
dissolves
Explanation: In an unsaturated solution,
additional solute will dissolve, whereas in a saturated solution, no more
solute will dissolve.
39. What is the dispersed phase in a foam?
A) Liquid bubbles
B) Solid particles
C) Gas bubbles
D) Liquid solution
Answer: C) Gas bubbles
Explanation: In a foam, the dispersed phase is
gas bubbles dispersed in a liquid.
40. Which of the following mixtures is an
example of a liquid in a liquid solution?
A) Vinegar in water
B) Sand in water
C) Iron filings in water
D) Oil and water
Answer: A) Vinegar in water
Explanation: Vinegar in water is a solution
where both are liquids and mix uniformly.
41. What is the purpose of using a separating
funnel in separating mixtures?
A) To dissolve solutes
B) To separate soluble solids
C) To separate immiscible liquids
D) To evaporate liquids
Answer: C) To separate immiscible liquids
Explanation: A separating funnel is used to
separate two immiscible liquids based on their different densities.
42. What does a homogeneous mixture look like?
A) The components are visibly different
B) It has a uniform composition throughout
C) It separates into layers
D) It has a cloudy appearance
Answer: B) It has a uniform composition
throughout
Explanation: A homogeneous mixture looks
uniform throughout because its components are evenly distributed.
43. How can you separate a mixture of sand and
salt using filtration and evaporation?
A) Mix the sand and salt, then use evaporation
B) Dissolve the salt in water, filter out the
sand, then evaporate the water
C) Use a magnet to separate the salt
D) Use a centrifuge
Answer: B) Dissolve the salt in water, filter
out the sand, then evaporate the water
Explanation: First dissolve the salt in water,
then filter out the sand, and finally evaporate the water to get the salt.
44. What is an example of a liquid in solid
solution?
A) Air
B) Alloy
C) Saltwater
D) Gelatine
Answer: D) Gelatine
Explanation: Gelatine is a gel where a liquid
is dispersed in a solid matrix, making it a liquid in solid solution.
45. What would you use to separate a mixture
of sand and salt without dissolving?
A) Centrifugation
B) Chromatography
C) Filtration
D) Evaporation
Answer: C) Filtration
Explanation: Filtration is suitable for
separating sand from salt without dissolving, as it removes solid particles
from a mixture.
46. Which of the following is a property of a
suspension?
A) Uniform particle size
B) Particles do not settle
C) Particles can be seen and will settle over
time
D) Solution has a clear appearance
Answer: C) Particles can be seen and will
settle over time
Explanation: Suspensions have visible
particles that eventually settle out when left undisturbed.
47. What method would you use to separate
different pigments in ink?
A) Filtration
B) Evaporation
C) Chromatography
D) Centrifugation
Answer: C) Chromatography
Explanation: Chromatography separates
different pigments based on their movement through a medium.
48. Which process is used to separate liquids
with different boiling points?
A) Filtration
B) Distillation
C) Chromatography
D) Evaporation
Answer: B) Distillation
Explanation: Distillation separates liquids
with different boiling points by heating and then condensing the vapor.
49. What type of mixture is soda?
A) Solution
B) Suspension
C) Colloid
D) Emulsion
Answer: A) Solution
Explanation: Soda is a solution of carbon
dioxide in water, making it a homogeneous mixture.
50. Which technique would you use to purify a
solvent from a solution?
A) Filtration
B) Distillation
C) Chromatography
D) Centrifugation
Answer: B) Distillation
Explanation: Distillation is used to purify
solvents by separating them based on boiling points, leaving impurities behind.
Summary
This MCQs covers the basics of different types of mixtures (homogeneous, heterogeneous, colloids, suspensions) and the methods used to separate them (filtration, evaporation, distillation, chromatography, separating funnel). Understanding these concepts helps in recognizing and analyzing various substances and their interactions.
Read More: Important 50nos MCQ for CBSE Class 9 Science Chapter 2: Is Matter Around Us Pure ( Part-2).