Class 9 Chemistry MCQs: Separation Techniques

MCQs (sample)

Showing 25 questions from this chapter. For a full timed test, use “Start online test”.

1. 1. What is filtration primarily used for?

   • To separate components of a mixture containing an undissolved solid in a liquid.
   • To dissolve solid substances in a liquid.
   • To increase the temperature of a mixture.
   • To combine two homogeneous mixtures.
   Answer & explanation

   Correct: To separate components of a mixture containing an undissolved solid in a liquid.

   Filtration is a separation technique used to separate components of a mixture containing an undissolved solid in a liquid.

2. 2. What is typically found in a mixture?

   • Elements and/or compounds
   • Only solid substances
   • Only liquids
   • Gases only
   Answer & explanation

   Correct: Elements and/or compounds

   A mixture contains elements and/or compounds that are not chemically combined together.

3. 3. What is evaporation primarily used for?

   • Separating a solid from a liquid mixture
   • Mixing liquids
   • Heating solids
   • Cooling gases
   Answer & explanation

   Correct: Separating a solid from a liquid mixture

   Evaporation is a separation method used to separate components of a mixture where a solid is dissolved in a liquid.

4. 4. What is crystallization primarily used for?

   • Purification of substances
   • Heating solutions
   • Dissolving solids
   • Cooling liquids
   Answer & explanation

   Correct: Purification of substances

   Crystallization is primarily employed as a technique for purification of substances.

5. 5. What is distillation primarily used for?

   • To separate components of a liquid mixture
   • To cool liquids
   • To combine different liquids
   • To solidify liquids
   Answer & explanation

   Correct: To separate components of a liquid mixture

   Distillation is used to separate components of a liquid mixture by heating and cooling, based on differences in volatility.

6. 6. What is an example of a heterogeneous mixture?

   • Brine solution
   • Sand in water
   • Sugar in water
   • Vinegar
   Answer & explanation

   Correct: Sand in water

   A heterogeneous mixture is one where the solute particles are not evenly distributed, such as sand in water.

7. 7. What is used to separate components of a mixture?

   • Physical properties
   • Chemical reactions
   • Nuclear fusion
   • Biological processes
   Answer & explanation

   Correct: Physical properties

   Components of a mixture can be physically separated using methods that exploit their physical properties.

8. 8. Which factor increases the rate of evaporation by providing more kinetic energy to particles?

   • Pressure
   • Temperature
   • Surface area
   • Inter-molecular forces
   Answer & explanation

   Correct: Temperature

   Increasing the temperature of the substance heats it up, leading to greater kinetic energy and an increased rate of evaporation.

9. 9. What happens to the solute when it reaches saturation in a solvent?

   • It completely dissolves
   • It remains undissolved and settles down
   • It evaporates
   • It forms a gas
   Answer & explanation

   Correct: It remains undissolved and settles down

   At saturation, the added solute remains undissolved and settles down at the bottom of the container.

10. 10. What is the product called that is obtained after the condensation of vapor in distillation?

    • Distillate
    • Mixture
    • Solvent
    • Solute
    Answer & explanation

    Correct: Distillate

    The liquid obtained from the condensation of vapor is called the distillate.

11. 11. What do we call the residue left behind after filtration?

    • Filtrate
    • Solvent
    • Insoluble solid
    • Solution
    Answer & explanation

    Correct: Insoluble solid

    Insoluble solid substances left behind after filtration are called residues.

12. 12. Which of the following is NOT a common method of separation?

    • Filtration
    • Evaporation
    • Condensation
    • Magnetic separation
    Answer & explanation

    Correct: Condensation

    Condensation is not listed as a common method of separation for mixtures.

13. 13. How does pressure affect the rate of evaporation?

    • Increases the rate of evaporation
    • Decreases the rate of evaporation
    • Has no effect
    • Depends on temperature
    Answer & explanation

    Correct: Decreases the rate of evaporation

    An increase in pressure makes it difficult for the liquid to convert to a gaseous form, therefore decreasing the rate of evaporation.

14. 14. Which of the following is an application of crystallization?

    • Obtaining pure salt from seawater
    • Cooking food
    • Separating gases
    • Reducing temperature
    Answer & explanation

    Correct: Obtaining pure salt from seawater

    One of the important applications of crystallization is obtaining pure salt from seawater.

15. 15. At what point does boiling occur during distillation?

    • When vapor pressure equals atmospheric pressure
    • When the liquid reaches room temperature
    • When the liquid freezes
    • When the liquid is mixed with air
    Answer & explanation

    Correct: When vapor pressure equals atmospheric pressure

    Boiling occurs when the vapor pressure of the liquid is equivalent to the atmospheric pressure.

16. 16. What type of filtration uses a Buchner funnel?

    • Gravity filtration
    • Cold filtration
    • Vacuum filtration
    • Biological filtration
    Answer & explanation

    Correct: Vacuum filtration

    Vacuum filtration uses a Buchner funnel to separate solid from liquid under vacuum pressure.

17. 17. What is a solution composed of?

    • A solute and a solvent
    • Only solids
    • Only gases
    • Mixtures of elements only
    Answer & explanation

    Correct: A solute and a solvent

    A solution consists of a solute, which is a solid, dissolved in a solvent, which is a liquid.

18. 18. Why do substances with strong inter-molecular forces have a lower rate of evaporation?

    • They vaporize easily
    • They require less energy to evaporate
    • They require greater energy to break bonds
    • They have higher temperatures
    Answer & explanation

    Correct: They require greater energy to break bonds

    Stronger inter-molecular forces require more energy to overcome, resulting in a lower rate of evaporation.

19. 19. What indicates that a solution is saturated during crystallization?

    • The solution becomes cloudy when dipped with a glass rod
    • The solution becomes clear
    • The solution evaporates completely
    • The crystals float on top
    Answer & explanation

    Correct: The solution becomes cloudy when dipped with a glass rod

    A drop becomes cloudy and crystals start to form when the solution is saturated.

20. 20. In which type of distillation is a fractionating column used?

    • Simple distillation
    • Fractional distillation
    • Steam distillation
    • Vacuum distillation
    Answer & explanation

    Correct: Fractional distillation

    Fractional distillation uses a fractionating column to create a temperature gradient for better separation of components.

21. 21. The main mechanism of filtration separates particles based on what characteristic?

    • Color
    • Size
    • Density
    • Temperature
    Answer & explanation

    Correct: Size

    Filtration separates solid matter from a liquid mixture based on the difference in sizes between the particles.

22. 22. Which separation method exploits the difference in density?

    • Filtration
    • Centrifugation
    • Magnetic separation
    • Evaporation
    Answer & explanation

    Correct: Centrifugation

    Centrifugation exploits differences in density to separate components of a mixture.

23. 23. What happens in an enclosed space during the evaporation process?

    • Liquid stops evaporating instantly
    • Liquid evaporates until air saturation is achieved
    • Gases condense immediately
    • No liquid transforms to gas
    Answer & explanation

    Correct: Liquid evaporates until air saturation is achieved

    In an enclosed space, a liquid continues to vaporize until air saturation is achieved.

24. 24. How do we identify pure substances in laboratory settings?

    • By measuring their density
    • By checking their color
    • By checking their melting and boiling points
    • By observing their size
    Answer & explanation

    Correct: By checking their melting and boiling points

    In school laboratories, the melting or boiling points are used to determine the purity of substances.

25. 25. What is one application of distillation mentioned in the content?

    • Making ice cream
    • Making distilled water
    • Making gas
    • Making vinegar
    Answer & explanation

    Correct: Making distilled water

    Distillation is used to make distilled water, among other applications mentioned.