Distillation Practice Questions
20 free Distillation practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is distillation mainly used for?
- A Separating iron filings using a strong magnet
- B Changing a solid directly into gas without melting
- C Separating substances by their boiling points
- D Mixing together two completely insoluble liquids
Correct answer: Separating substances by their boiling points
Distillation separates components of a mixture by using differences in their boiling points. The liquid with the lower boiling point vaporizes first and is then condensed.
Which two processes are involved in distillation?
- A Filtration and sedimentation
- B Magnetism and crystallization
- C Evaporation and condensation
- D Freezing and melting only
Correct answer: Evaporation and condensation
In distillation, a liquid is first heated to form vapour. The vapour is then cooled and condensed back into liquid.
Which part of a simple distillation setup cools vapour back into liquid?
- A Thermometer bulb
- B Round-bottom flask
- C Condenser tube
- D Bunsen burner
Correct answer: Condenser tube
The condenser cools the hot vapour produced during heating. As the vapour loses heat, it changes back into liquid and is collected.
The liquid collected after condensation during distillation is called the:
- A Residue
- B Solute
- C Precipitate
- D Distillate
Correct answer: Distillate
The distillate is the purified liquid collected after vapour condenses. The less volatile or non-volatile substances remain behind as residue.
Which mixture can be separated by simple distillation?
- A Sand mixed with iron filings
- B Oil mixed with water
- C Salt dissolved in water
- D A mixture of rice and stones
Correct answer: Salt dissolved in water
Simple distillation can separate water from a salt solution because water vaporizes while salt remains behind. The water vapour condenses to give distilled water.
Why does salt remain behind when salt water is distilled?
- A Salt turns into oxygen
- B Salt becomes magnetic
- C Salt has a much higher boiling point than water
- D Salt actually evaporates much faster than water does
Correct answer: Salt has a much higher boiling point than water
Water boils and forms vapour at a much lower temperature than salt. The dissolved salt remains in the flask as a non-volatile residue.
Which liquid distils first when a mixture contains liquids with different boiling points?
- A The liquid with the highest density
- B The liquid with the darkest colour
- C The liquid with the lowest boiling point
- D The liquid with only the largest total volume
Correct answer: The liquid with the lowest boiling point
A liquid with a lower boiling point vaporizes before liquids with higher boiling points. Therefore, it is usually collected first during distillation.
Fractional distillation is most useful for separating liquids that:
- A Have very different colours
- B Are all solids
- C Are magnetic
- D Have close boiling points
Correct answer: Have close boiling points
Fractional distillation is used when the boiling points of liquids are close to each other. A fractionating column helps separate the vapours more effectively.
Which apparatus is especially important in fractional distillation?
- A Filter funnel
- B Magnet
- C Fractionating column
- D Evaporating dish only
Correct answer: Fractionating column
A fractionating column provides repeated vaporization and condensation. This improves separation of liquids with similar boiling points.
Which industrial process uses fractional distillation on a large scale?
- A The industrial process of making curd from milk
- B The slow rusting process of iron
- C Separation of crude oil into fractions
- D The simple burning of paper
Correct answer: Separation of crude oil into fractions
Crude oil is separated into useful fractions by fractional distillation. Different fractions are collected at different temperature ranges based on their boiling points.
During distillation of impure water, what is usually left behind in the flask?
- A Only pure water vapour itself
- B Oxygen gas only
- C Non-volatile impurities
- D Condensed distillate
Correct answer: Non-volatile impurities
Non-volatile impurities do not vaporize with water. They remain behind in the distillation flask while purified water is collected as distillate.
What is the main purpose of cold water circulation in a condenser?
- A To heat the vapour even further still
- B To dissolve the solute
- C To cool vapour and help it condense
- D To make the flask heavier
Correct answer: To cool vapour and help it condense
Cold water removes heat from the hot vapour passing through the condenser. This cooling changes the vapour back into liquid.
In a condenser, water is usually allowed to enter from the lower end because:
- A It makes the vapour move much faster than before
- B It completely prevents all boiling from occurring
- C It keeps the condenser jacket completely filled
- D It somehow changes the salt directly into water
Correct answer: It keeps the condenser jacket completely filled
Water entering from the lower end pushes air out and keeps the condenser jacket filled. This provides better cooling of the vapour.
Which statement best describes simple distillation?
- A It separates a liquid from dissolved solids or liquids with widely different boiling points
- B It separates magnetic substances from a mixture using a magnet, based on their magnetic properties
- C It separates a mixture of gases from each other purely based on their different colours
- D It separates a mixture of solids from each other by picking out the pieces with the hand
Correct answer: It separates a liquid from dissolved solids or liquids with widely different boiling points
Simple distillation works well when one component is volatile and the other is non-volatile, or when liquids have very different boiling points. It depends on vaporization followed by condensation.
Which mixture is best separated by fractional distillation rather than simple distillation?
- A Ethanol and water
- B Sand and water
- C Copper sulfate and water
- D Common salt and water
Correct answer: Ethanol and water
Ethanol and water are miscible liquids with relatively close boiling points. Fractional distillation gives better separation than simple distillation.
What happens to the temperature reading when a pure liquid is boiling during distillation?
- A It remains nearly constant at its boiling point
- B It drops to zero almost immediately
- C It keeps increasing steadily throughout
- D It becomes completely unrelated to the liquid's boiling point throughout the process
Correct answer: It remains nearly constant at its boiling point
A pure liquid boils at a fixed temperature under constant pressure. During boiling, the temperature stays nearly constant because heat is used to change liquid into vapour.
Why is a thermometer used in distillation?
- A To monitor the temperature of vapour being distilled
- B To stir the mixture continuously while heating it
- C To filter out solid particles from the vapour stream automatically
- D To collect the distillate as it drips from the condenser
Correct answer: To monitor the temperature of vapour being distilled
The thermometer helps identify which component is vaporizing by showing the vapour temperature. This is especially useful when separating liquid mixtures.
Which property of a liquid is most important in distillation?
- A Boiling point
- B Shape
- C Hardness
- D How easily it dissolves other substances
Correct answer: Boiling point
Distillation depends on differences in boiling points of substances. Liquids with lower boiling points vaporize before those with higher boiling points.
What is the residue in a distillation process?
- A The substance left behind after distillation
- B The condensed vapour collected in the receiving flask
- C The cooling water in the condenser
- D The gas used for heating
Correct answer: The substance left behind after distillation
Residue is the material left in the flask after the volatile component has distilled. It often includes dissolved solids or higher-boiling substances.
Distillation is a physical separation method because:
- A No new chemical substance is formed
- B It produces fire as the main result
- C It changes atoms into entirely new chemical elements
- D It can occur only in living cells
Correct answer: No new chemical substance is formed
Distillation separates substances by physical properties such as boiling point. The substances do not chemically change during the process.