Chemistry · Science General

Separation Techniques

813 Questions

Separation techniques involve physical methods to isolate mixtures, including distillation, filtration, and crystallization. Competitive exams frequently test these foundational concepts. Review the exact processes to enhance problem solving speed.

Distillation and evaporationCrystallization processFiltration methodsSeparating dissolved solidsChromatography and mass techniques

Separation Techniques Questions

Multiple choice

A mixture of salt and sand can be separated by

  1. sublimation

  2. dissolving water

  3. gravity separation

  4. dry distillation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Salt (NaCl) is water-soluble while sand (SiO2) is not. Adding water dissolves the salt, leaving sand as insoluble residue. The salt can then be recovered by evaporating the water. The option wording 'dissolving water' is awkward but the intended meaning is correct.

Multiple choice

A mixture of water and alcohol can be separated by ____.

  1. Filtration

  2. Evaporation

  3. Distillation

  4. Decantation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A mixture of water and alcohol can be separated by distillation (option C). Distillation works because water and alcohol have different boiling points (100°C for water, 78°C for ethanol), allowing the alcohol to vaporize first. Filtration separates solids from liquids, evaporation leaves solids behind, and decantation separates immiscible liquids of different densities.

Multiple choice

A mixture of iron filings and sand can be separated by ______.

  1. Heating

  2. Sublimation

  3. Hand picking

  4. Magnetic separation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Iron filings are magnetic and can be attracted by a magnet while sand is non-magnetic. This property difference allows magnetic separation to effectively isolate the iron from the sand mixture.

Multiple choice

Name the process which is used to separate various constituents of petroleum.

  1. Oil refinery

  2. Distillation

  3. Petroleum refinery

  4. Refining
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oil refinery and petroleum refinery are the places where petroleum is separated into its constituents. Distillation is the process of separating a mixture of two miscible liquids having a boiling point difference more than 25 k. Crude oil is a mixture of many products having a difference of less than 25 k in the boiling points. Refining is the process by which petroleum is separated into its various constituents by fractional distillation.

Multiple choice

A mixture of water and alcohol can be separated by

  1. filtration

  2. distillation

  3. evaporation

  4. decantation

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water and alcohol form a homogeneous mixture that cannot be separated by filtration, decantation, or simple evaporation. Distillation works because water (boiling point 100°C) and ethanol (78°C) have different boiling points, allowing them to be separated through controlled heating and condensation.

Multiple choice

What is the method used to separate cream from milk?

  1. Filtration

  2. Centrifugation

  3. Crystallisation

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Centrifugation uses centrifugal force to separate substances of different densities. Cream (fat) is less dense than skim milk, so it rises to the top and can be separated by spinning. Filtration separates solids from liquids using a filter. Crystallisation purifies dissolved solids from a solution.

Multiple choice

Micromanipulator is used for the isolation of microorganism in

  1. streak plate method

  2. pour plate method

  3. enrichment culture technique

  4. single cell isolation technique

  5. serial dilution technique
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Micromanipulator is used in single cell isolation technique for the isolation of microorganisms in pure culture. It is an equipment used to pick up a single cell and transferr to suitable medium.

Multiple choice

Which of the following is not a method of isolation of microbes?

  1. Pour plate method

  2. Streak plate method

  3. Serial dilution method

  4. Sterilisation method

  5. Enrichment culture technique
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sterilization method is not a isolation method of microbes. A steam temperature of 121oC is usually maintained for wet sterilization in autoclave at pressure 15 lbs/inch2 (1.05 kg/sq.cm). Fifteen minutes of duration is sufficient for sterilization. Culture media are wet sterilized because they are either liquid or semi-solid gels containing water.

Multiple choice

Which of the following is not an application of centrifugation?

  1. For separating textiles.

  2. Removing fat from milk to produce skimmed milk.

  3. Separating different grades of plastic.

  4. Separation of urine components and blood components in forensic lab.

  5. Separation of water particles from clothes while spin drying in washing machine.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The method used is gravity separation.

Multiple choice

In which of the following situations is sieving used?

  1. Used for the separation of slightly larger sized impurities.

  2. Used to separate heavier and lighter components of a mixture.

  3. Used when components of a mixture have different sizes.

  4. Used to separate two immiscible liquids.

  5. Used to remove tiny particles from liquids.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The method used is sieving.