This set of Food Processing Unit Operations Multiple Choice Questions & Answers (MCQs) focuses on “Mechanism of Crystallization”.
1. What is co-crystallization?
a) Parallel arrangement in crystallization
b) Catalysts
c) Cross arrangements in crystallization
d) Seeding agents
View Answer
Explanation: Co crystallization or seedling agents are the process by which a solid forms, where the molecules are very organized and forms into a structure known as a crystal.
2. What is the mechanism of crystallization?
a) Nucleation, crystal maturation and growth
b) Nucleation and growth
c) Nucleation, growth, and crystal maturation
d) Nucleation and crystal maturation
View Answer
Explanation: The mechanism of crystallization includes in the order of nucleation, growth and finally maturation of the crystals, thus leading to the crystalline lattice.
3. What is crystallization temperature?
a) Temperature at which the brine solution is partially saturated
b) Temperature at which the brine solution is fully saturated
c) Temperature at which the solute and solvent is fully saturated
d) Temperature at which the solute and solvent is partially saturated
View Answer
Explanation: The thermodynamic crystallization temperature which is also called as true crystallization temperature is defined as the temperature at which the brine solution is completely saturated with respect to the least soluble salt.
4. Is crystal size controlled by temperature?
a) True
b) False
View Answer
Explanation: Under crystal nucleation, the process follows the number of formed crystal nuclei increases with supersaturation. When the temperature of crystallization process changes therefore the crystal size is also changed.
5. Which of the following statements about evaporative crystallization are correct?
Statement 1:The process depends on evaporation of the solvent.
Statement 2:This process does not create vapor or suspension of crystals in mother liquor.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: In evaporative crystallization, the process is due to the evaporation of solvent. So, therefore this process creates vapor and suspension of crystals in mother liquor. The evaporation heat is added in the captured vapor stream.
6. Who invented crystallization?
a) Jabir ibn Hayyan
b) Charles Chamberland
c) Willis Carrier
d) Clarence Birdseye
View Answer
Explanation: Jabir ibn Hayyan invented crystallization. Charles Chamberland developed the first pressure steam sterilizer. Willis Carrier invented the chillers. Clarence Birdseye developed processes for freezing fish based on quick freezing.
7. What is special form of cooling crystallization process?
a) Freeze crystallization
b) Slow crystallization
c) Melt crystallization
d) Quick crystallization
View Answer
Explanation: The melt crystallization is observed as a distinct form of cooling crystallization process. The main difference with cooling crystallization from other method is the nonexistence of solvents which suggests that this process is operated near to the melting point of the pure component.
8. Which process is called as a counter-current cascade?
a) Fractional crystallization
b) Cooling crystallization
c) Precipitation
d) Evaporative crystallization
View Answer
Explanation: Fractional crystallization is called as a counter-current cascade. It is used to describe a process where repeated crystallization steps. These are used to increase the purity of the product and to increase the yield of the process.
9. Which of the following statements about fractional crystallization are correct?
Statement 1: In this process, repeated crystallization takes place.
Statement 2: It increases the purity of the material.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: Fractional crystallization is used to describe a process where repeated crystallization steps. These are used to increase the purity of the product and to increase the yield of the process.
10. Is cooling crystallization is more energy friendly than evaporative crystallization?
a) True
b) False
View Answer
Explanation: The cooling crystallization is typically more energy friendly than the evaporative crystallization. In cooling crystallization process the feed is cooled in heat exchanger, where it is situated inside the crystallizer. The crystallizer wall can be used as internal heat exchanger.
Sanfoundry Global Education & Learning Series – Food Processing Unit Operations.
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