This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Crystallisation”.
1. Which of the following is not a common method used for purification?
a) Sublimation
b) Crystallisation
c) Electrolysis
d) Chromatography
View Answer
Explanation: Sublimation, crystallisation, distillation, differential extraction and chromatography are some of the common methods used for purification. Electrolysis process is not used for this purpose.
2. Crystallisation is based on the ____________
a) Difference in melting point
b) Difference in boiling point
c) Difference in pressure
d) Difference in solubility
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Explanation: Crystallisation is based on the difference in the solubility of the compound and the impurities in a suitable solvent.
3. Which of the following is the example of crystallisation process?
a) Purification of alum
b) Purification of sea water
c) Separation of gases from air
d) None of the mentioned
View Answer
Explanation: An impure sample of alum or copper sulphate is purified by crystallisation process. Purification of sea water is example of distillation process.
4. At room temperature, the impure compound in crystallisation is ____________
a) Soluble
b) Sparingly soluble
c) Insoluble
d) None of the mentioned
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Explanation: The impure compound is sparingly soluble in a solvent at room temperature but appreciably soluble at higher temperatures.
5. Which of the following is known as mother liquor?
a) Solvent
b) Solute
c) Solution
d) Filtrate
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Explanation: The filtrate is also known as mother liquor. A mother liquor is the part of a solution that is left over after crystallization. It is encountered in chemical processes including sugar refining.
6. The solution of impure compound and solvent is concentrated to get ____________
a) Unsaturated solution
b) Undersaturaed solution
c) Saturated solution
d) Oversaturated solution
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Explanation: The solution of impure compound and solvent is concentrated to get a saturated solution. The solution is filtered to remove insoluble impurities.
7. Insoluble impurities from solution during crystallization are removed by ____________
a) Drying
b) Filtration
c) Heating
d) Cooling
View Answer
Explanation: Insoluble impurities from solution during crystallization are removed by filtration. The solution is filtered to remove insoluble impurities.
8. The solution which is obtained after filtration is ____________
a) Suspended solution
b) Clear solution
c) Colloidal solution
d) None of the mentioned
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Explanation: The solution which is obtained after filtration is a clear solution. The solution is filtered to remove insoluble impurities.
9. Crystal phases can be inter-converted by varying ____________
a) Temperature
b) Pressure
c) Size
d) Viscosity
View Answer
Explanation: Crystal phases can be inter-converted by varying factors such as temperature.
10. The nature of the crystallization process is governed by _____________
a) Thermodynamics
b) Kinetic factors
c) Thermodynamics and Kinetic factors
d) None of the mentioned
View Answer
Explanation: The nature of the crystallization process is governed by both thermodynamic and kinetic factors.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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