This set of Food Processing Unit Operations online quiz focuses on “Crystallization – Supersaturation”.
1. What happens when supersaturated solution is cooled down?
a) Solid crystals will dissolve into the water
b) Solid crystals remain as it is in water
c) Solid crystals will grow in bigger size
d) Solid crystals will shrink into smaller size
View Answer
Explanation: The solid crystals dissolve into the water in the hydrated crystals forming a supersaturated solution. Adding small crystal in the supersaturated solution causes the liquid to change to the solid.
2. What is supersaturation?
a) Has a higher vapor pressure than that of vapor pressure of that compound
b) Has a lower vapor pressure than that of vapor pressure of that compound
c) Has equal pressure similar to vapor pressure of that compound
d) Does not depend on vapor pressure of that compound
View Answer
Explanation: Supersaturation is defined as to a vapor of a compound which has a higher pressure than vapor pressure of that compound. It is also defined as the solution containing more of the dissolved material than equilibrium by the solvent at standard conditions.
3. What is the principle of supersaturation in vapor phase?
a) Poynting effect
b) Gibbs–Thomson effect and Poynting effect
c) Kelvin equation and Gibbs–Thomson effect
d) Kelvin equation, Gibbs–Thomson effect and Poynting effect
View Answer
Explanation: The supersaturation in vapor phase is based on the surface tension of liquids through Kelvin equation, Gibbs–Thomson effect and Poynting effect.
4. Which of the industry uses the In vivo supersaturation phenomenon?
a) Fashion industry
b) Pharma industry
c) Food industry
d) Cement industry
View Answer
Explanation: Pharma industry uses In vivo supersaturation phenomenon as orally administered components that undergo supersaturation as they move through the gastrointestinal tract.
5. How can supersaturated solution used in marine ecologist?
a) To study the activity of organisms
b) Tostudy the concentration of water
c) To study the patterns of the organisms
d) To detect the populations adaption
View Answer
Explanation: The supersaturated solutions are used for marine ecologists to study the activity of organisms and populations. Photosynthetic organisms release O2 gas into the water. Therefore, area of the ocean is supersaturated with O2 gas.
6. What is the other name for super-cooling?
a) Undercooling
b) Overcooling
c) Cooling
d) Super cooling
View Answer
Explanation: Super-cooling is also termed as under-cooling. In this process, the temperature of the of liquid or gas is lowered below its freezing point devoid of it changing to solid state.
7. What is the first step in crystallization?
a) Nucleation
b) Cooling
c) Super-cooling
d) Pre-crystallization
View Answer
Explanation: Nucleation is the first step in the formation of crystals. The liquids and solutions are cooled down where the liquid or solution is considerably less thermodynamically stable than the crystal.
8. What is classical nucleation theory?
a) To study the kinetics of nucleation
b) To study the nucleation statists
c) To study the concentration of nucleation
d) To study the nucleation temperature
View Answer
Explanation: Study of the kinetics of nucleation uses the classical nucleation theory which is the most common theoretical model. Homogeneous nucleation is fewer than heterogeneous nucleation.
9. Which of the following statements about seed crystal are correct?
Statement 1: Seed crystal provides a nucleation site.
Statement 2: The recrystallization is done by seed crystal.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: Seed crystal provides a nucleation site on which crystals begin to grow. The recrystallization of the excess dissolved solute in a supersaturated solution can be originated by adding small crystal of solute is called a seed crystal.
10. What affects crystal growth?
a) Temperature
b) Pressure
c) Evaporation
d) Evaporation, pressure and temperature
View Answer
Explanation: Crystal growth is affected by the amount of dissolved material, evaporation, pressure and temperature. The higher the amount of dissolved material in the solvent, the bigger the crystals grow.
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