Engineering Chemistry Multiple Choice Questions on “Steam Distillation”.
1. In steam distillation, the liquid boils when the sum of vapour pressure due to organic liquid and due to water becomes ____________
a) Greater than atmospheric pressure
b) Lesser than atmospheric pressure
c) Equals to atmospheric pressure
d) None of the mentioned
Answer: c
Clarification: In steam distillation, the liquid boils when the sum of vapour pressure due to organic liquid and due to water becomes equal to the atmospheric pressure. It is a type of distillation of a liquid in a current of steam, used especially to purify liquids that are not very volatile and are immiscible with water.
2. The organic liquid in steam distillation vaporizes at ____________
a) Lower temperature than its boiling point
b) Higher temperature than its boiling point
c) At its boiling point
d) None of the mentioned
Answer: a
Clarification: The organic liquid in steam distillation vaporizes at lower temperature than its boiling point.
3. Steam distillation process is used to separate substances which are ____________
a) Steam volatile
b) Steam volatile and immiscible with water
c) Steam volatile and miscible with water
d) All of the mentioned
Answer: b
Clarification: Steam distillation process is used to separate substances which are steam volatile and immiscible with water. It is a type of distillation of a liquid in a current of steam, used especially to purify liquids that are not very volatile and are immiscible with water.
4. What type of mixture is collected in round bottom flask after passing through a steam generator?
a) Mixture of volatile organic compound and water
b) Mixture of nonvolatile organic compound and water
c) Mixture of nonvolatile inorganic compound and steam
d) Mixture of volatile organic compound and steam
Answer: d
Clarification: Mixture of volatile organic compound and steam is collected in round bottom flask after passing through steam generator.
5. Which of the following property is not possessed by the organic solvent required to separate organic compound with water?
a) It is immiscible with water
b) It is less volatile than water
c) It is easily vaporisable
d) Organic compound is more soluble in it
Answer: b
Clarification: Organic solvent required to separate organic compound with water is more volatile liquid than water. All the other mentioned properties are possessed by the organic solvent required to separate organic compound with water.
6. Which of the following is the upper layer in differential extraction?
a) Solvent layer
b) Solute layer
c) Aqueous layer
d) None of the mentioned
Answer: a
Clarification: Solvent layer is the upper layer in differential extraction. Differential extraction refers to the process by which the DNA from two different types of cells can be extracted without mixing their contents.
7. When does the organic compound be present in the upper solvent layer in differential extraction?
a) Before the extraction
b) During the extraction
c) After the extraction
d) It is always present in the upper layer
Answer: c
Clarification: The organic compound is present in the solvent layer after the extraction. Differential extraction refers to the process by which the DNA from two different types of cells can be extracted without mixing their contents
8. The organic compound in differential extraction is recovered from the organic solvent by ____________
a) Distillation
b) Fractional crystallisation
c) Steam crystallisation
d) Sublimation
Answer: a
Clarification: The organic compound in differential extraction is recovered from the organic solvent by distillation by evaporation.
9. The pure solvent after the differential extraction cannot be used again for the extraction.
a) True
b) False
Answer: b
Clarification: The pure solvent after the differential extraction can be used again for the extraction because it remains unaltered.
10. Aniline is separated from aniline-water mixture using ____________
a) Fractional distillation
b) Fractional crystallisation
c) Steam distillation
d) All of the mentioned
Answer: c
Clarification: Aniline is separated from aniline-water mixture using steam distillation. Steam distillation is a special type of distillation (a separation process) for temperature sensitive materials like natural aromatic compounds.