Category: Food Processing Unit Operations Objective Questions

250+ TOP MCQs on Crystallization – Nucleation Mechanism and Answers

Food Processing Unit Operations Multiple Choice Questions on “ Crystallization – Nucleation Mechanism”.

1. What is nucleation in crystallization?
a) It is the initial step in crystallization
b) It is the final step in crystallization
c) It is the step where nucleus is added
d) It is the sub category crystallization
Answer: a
Clarification: Nucleation is the initial process that occurs in the formation of a crystal from a solution, a liquid, or a vapor, in which a small number of molecules arranged in a pattern.

2. How to initiate crystallization?
a) Adding seed crystals
b) Adjusting temperature
c) Adjusting pressure
d) Adjusting concentration
Answer: a
Clarification: Crystallization can be spontaneous or can be done by addition of small amount of the seed crystal or the pure compound to the saturated solution.

3. How does temperature affect nucleation?
a) Nucleation is directly proportional to temperature
b) Nucleation is indirectly proportional to temperature
c) Nucleation and temperature are always at equilibrium
d) Nucleation and temperature does not depend on each other
Answer: b
Clarification: The decrease in nucleation centers at high temperature interprets that decrease in supersaturation, would increase in critical size of nucleus and free energy of nucleus formation.

4. What is nucleation in freezing?
a) Process of gathering of molecules into tiny clusters
b) It is the final step in freezing
c) It is the step where nucleus is added
d) It is the sub category freezing
Answer: a
Clarification: Nucleation is a process where the molecules or the atoms in a liquid start to gather into tiny clusters, arranging to form the crystal structure of the solid.

5. Which of the following statements about primary nucleation are correct?
Statement 1:The appearance of the first crystal is called primary nucleation time.
Statement 2:It describes the transition to a new phase.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: The time until the presence of the first crystal is called primary nucleation time, it refers to the first nucleus to form. It describes the transition to a new phase which does not rely on the new phase which is already present.

6. What is homogeneous nucleation?
a) Spontaneously generated nuclei
b) Randomly generated nuclei
c) Orderly generated nuclei
d) Randomly and spontaneously generated nuclei
Answer: d
Clarification: Homogeneous nucleation is the process by which nuclei that are randomly and spontaneously generated grow irreversibly to form a new phase.

7. What is seeding in crystallization?
a) It is the initial step in crystallization
b) It is the final step in crystallization
c) It is the step where nucleus is added
d) It is the sub category crystallization
Answer: c
Clarification: Crystal seeding is the process of adding homogeneous or heterogeneous crystals to a crystallizing solution to nucleate and grow more crystals.

8. What are the factors that affect crystallization seedling?
a) Temperature and pressure
b) Polymorphism of the crystals and pressure
c) Crystal size distribution and temperature
d) Crystal size distribution and polymorphism of the crystals
Answer: d
Clarification: Crystal seeding is the technique to add homogeneous or heterogeneous crystals to a crystallizing solution for nucleating and growing of more crystals. This is done by controlling the polymorphism of the crystals that are formed and crystal size distribution.

9. Which of the following statements about secondary crystallization are correct?
Statement 1:Secondary nucleation is the formation of nuclei from pre-existing crystals.
Statement 2: Only secondary nucleation increases the number of crystals in the system.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: a
Clarification: Secondary nuclei are crystal nuclei that are produced from a pre-existing crystal. Primary and secondary nucleation increases the number of crystals in the system and depends on crystals which are already present.

10. Is supersaturation the driving force for all solution crystallization processes?
a) True
b) False
Answer: a
Clarification: Supersaturation is the driving force for all solution crystallization processes where the supersaturated solution spontaneously separate into pure crystals of the solute and a less concentrated solution.

250+ TOP MCQs on Gas Liquid Equilibrium and Answers

Food Processing Unit Operations Multiple Choice Questions on “Gas Liquid Equilibrium”.

1. What is VLE?
a) Vapor liquid equal
b) Vapor liquid equilibrium
c) Vapor liquid estimation
d) Vapor liquid enthalpy
Answer: b
Clarification: The vapor liquid equilibrium (VLE) defines the distribution of chemical substances between the vapor phase and liquid phase. The equilibrium vapor pressure of a liquid is in overall intensely reliant on temperature.

2. What is the quality in percentage of saturated vapor?
a) 0%
b) 50%
c) 100%
d) 200%
Answer: c
Clarification: Vapor quality is the mass fraction in a saturated mixture that is vapor. It has a quality of 100%. Vapor quality is an intensive property. It is used only for single constituent mixes.

3. What is the quality in percentage of saturated liquid?
a) 0%
b) 50%
c) 100%
d) 200%
Answer: a
Clarification: Vapor quality is the mass fraction in a saturated mixture that is vapor. It has a quality of 0%. Vapor quality is an intensive property. It is used only for single constituent mixes.

4. Which of the following are not vapor liquid phase diagrams?
a) Boiling point diagrams
b) Txy, Pxy diagrams
c) Ternary diagrams
d) Freezing point diagrams
Answer: d
Clarification: Boiling point diagrams, Txy, Pxy diagrams, ternary diagrams and solubility diagrams are the vapor liquid phase diagrams. These diagrams signify a binary mix and all the compositions are expressed as mole fractions of the more volatile component.

5. What is the alternative name for bubble point temperature?
a) Dew point
b) Initial boiling point
c) Final boiling point
d) Bubble ruptures point
Answer: b
Clarification: Bubble point temperature is also called initial boiling point. It is the temperature at a given pressure, when a liquid consisting of two or more components is heated the first bubbles of the vapors are formed.

6. What is the alternative name for dew point temperature?
a) Bubble point tempertaure
b) Initial boiling point
c) Final boiling point
d) Bubble ruptures point
Answer: c
Clarification: The alternative name for dew point temperature is Final boiling point. It is the temperature to which air is cooled to become saturated with the water vapor. It is always lower than the air temperature.

7. Are these statements about the Henry’s law true?
Statement 1: Solubility of a gas in a liquid is indirectly proportional to the pressure of the gas.
Statement 2: It is applicable only when the pressure of the gas is not too high.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: c
Clarification: Solubility of a gas in a liquid is directly proportional to the pressure of the gas under equilibrium. Henry’s law is applicable only when the pressure of the gas is not too high and temperature is not too low. The gas should not undergo association or dissociation in the solution.

8. Which of the gas will not follow Henry’s law?
a) HCl gas
b) Oxygen
c) Hydrogen gas
d) Helium
Answer: a
Clarification: HCl gas does not follow Henry’s law as in solution HCl dissociate into ions H+ and Cl–. HCl is a strong acid and it interrelates with solvent and readily dissociate into its constituent ions. While Helium, oxygen gas and hydrogen gas do not dissociate on interaction with water so they follow Henry’s law.

9. Which of the following law is applied in respiratory physiology?
a) Raoult’s law
b) Henry’s law
c) Boyle’s law
d) Dalton’s law
Answer: b
Clarification: The main application of Henry’s law in respiratory physiology is to forecast gas dissolving in the alveoli and bloodstream during the gas exchange. The amount of oxygen that dissolves into bloodstream is proportional to the partial pressure of oxygen in alveolar air.

10. Which of the following is not the application of Henry’s Law?
a) To increase the solubility of carbon dioxide gas in soda water
b) In deep sea scuba diving
c) In respiratory physiology
d) To estimate the contribution of individual components by the system
Answer: d
Clarification: The applications of Henry’s Law are 1) Used in soda can packaging. 2) In deep sea scuba diving. 3) In respiratory physiology. Whereas Raoult’s Law is used to estimate the contribution of individual components of a liquid or solid mixture to the total pressure exerted by the system.

250+ TOP MCQs on Basic Drying Theory and Answers

Food Processing Unit Operations Multiple Choice Questions on “Basic Drying Theory”.

1. Lyophilization is also known as ____________
a) freezedrying
b) sundrying
c) tunneldrying
d) mechanicaldrying
Answer: a
Clarification: Lyophilization is also called as freeze drying. It is a process where biological material is preserved by removing the water from sample. It is a twostep process, first the sample is freeze and then dry it under a vacuum at low temperatures.

2. What is a triple point of pure water?
a) -0.01°C
b) 0.01°C
c) 0.1°C
d) -0.1°C
Answer: b
Clarification: The triple point of pure water is at 0.01°C. The triple point is the condition in which the temperature and pressure of all three phases (gas, liquid and solid) can coexist in equilibrium.

3. Phase diagram is a graphical representation of the ________ states of a substance under different conditions of temperature and pressure.
a) physical
b) chemical
c) electromagnetic
d) mechanical
Answer: a
Clarification: Phase diagram is a graphical depiction of the physical conditions of a matter under different conditions of temperature and pressure. It has temperature on the x-axis and pressure on the y-axis.

4. __________ diagrams represent the phase behavior of mixtures containing three components.
a) Ternary phase
b) Tertiary phase
c) Tri phase
d) Term phase
Answer: a
Clarification: The ternary phase represents the behavior of three components in a mixture with a triangular diagram. These diagrams provide the data which is precise and accurate of the various components.

5. The effect of ______on the system is seen only as a phase change.
a) Latent heat
b) Specific heat
c) Enthalpy
d) Entropy
Answer: a
Clarification: Latent heat can be defined as the heat that is released or absorbed by a system during constant temperature process. The effect is seen only as a phase change like boiling of water or the melting of ice.

6. The term triple point was coined by ___________
a) Rudolf Clausius
b) Thomas Young
c) Joseph Black
d) James Thomson
Answer: d
Clarification: Rudolf Clausius invented the term entropy. Thomas Young invented the term enthalpy. Joseph Black invented the term latent heat. The term triple point was coined by James Thomson.

7. What is the critical point of water?
a) 374°C
b) 157.5°C
c) 31.0°C
d) 240.9°C
Answer: a
Clarification: The critical point of water is 374°C. The critical point of sulphuric acid is 157.5°C. The critical point of supercritical carbon dioxideis 31.0°C. The critical point of ethanol is 240.9°C.

8. What are factors depending on rate of drying?
a) Initial moisture content of the product
b) Composition of raw material
c) Temperature, relative humidity
d) Initial moisture content, composition, temperature, relative humidity of the product.
Answer: d
Clarification: Drying rate is defined as the mass of water removed per unit time per unit area. It depends on initial moisture content, composition, temperature, relative humidity of the product, Size, shape and arrangement of stacking of the raw material.

9. Who discovered critical point?
a) Joseph Black
b) Charles Cagniard de la Tour
c) Henri Becquerel
d) Stephen Gray
Answer: b
Clarification: Joseph Black discovered latent heat. Charles Cagniard de la Tour discovered critical piont. Henri Becquerel discovered radiation. Stephen Gray discovered electrical conduction.

10. Does boiling point increase with pressure?
a) True
b) False
Answer: a
Clarification: At higher altitudes, the atmospheric pressure is much lower therefore the boiling point is also lower. The boiling point depends on pressure up to the critical point. It is directly proportional to the pressure. At the critical point the gas and liquid properties are same.

250+ TOP MCQs on Fluid Statics & Fluid Dynamics and Answers

Food Processing Unit Operations Multiple Choice Questions on “Fluid Statics and Fluid Dynamics”

1. The force per unit area in a fluid is called as __________
a) differential pressure
b) fluid pressure
c) dynamic pressure
d) absolute pressure

Answer: b
Clarification: The force per unit area in a fluid is called as fluid pressure. Since the fluid does not have any shape, the forces can be exerted in all directions such as gravitational force, external force on the fluid.

2. Which principle explains the buoyant force of a fluid?
a) Archimedes principle
b) Pascal’s principle
c) Bernoulli’s Principle
d) Newton’s second law of motion

Answer: a
Clarification: Archimedes principle states that the object partially or fully submerged in a fluid will experience a buoyant force which is equal to the fluid weight in which object is displaced.

3. Hydraulic system works on the basis of ____________
a) Archimedes principle
b) Pascal’s principle
c) Bernoulli’s Principle
d) Newton’s second law of motion

Answer: b
Clarification: Hydraulic system works on the basis of Pascal’s principle. This principle states that when pressure is applied to a closed system of fluid, the pressure is transmitted to every part of the fluid and also to the walls of the container in which fluid is enclosed.

4. Are these statements about the Fluid mechanics true?
Statement 1: Fluid mechanics is a branch in chemistry that involves study of fluids.
Statement 2: Fluid mechanics can be divided into 2 major categories.
a) True, False
b) True, True
c) False, True
d) False, False

Answer: c
Clarification: Fluid mechanics is a branch in physics that involves study of fluids such as liquids, plasma and gases. Fluid mechanics can be divided into 2 major categories. They are fluid statics (study based on fluids at rest) and fluid dynamics (study based on fluids in motion).

5. Which principle is used in designing the wings of airplanes?
a) Archimedes principle
b) Pascal’s principle
c) Bernoulli’s Principle
d) Newton’s second law of motion

Answer: c
Clarification: Bernoulli’s Principle is used in designing the wings of airplanes. According to the law of aerodynamics called Bernoulli’s principle, fast moving air has low pressure than slow moving air which has high pressure, so therefore pressure above wings is lower compared to pressure below the wings and this creates the lift in the plane that powers it to fly upwards.

6. Which of the following statements about applications of Pascal law in daily life are precise?

  • Statement 1: It is used in hydraulic pumps and hydraulic press.
  • Statement 2: It is not used in braking system in the vehicles.

a) True, False
b) True, True
c) False, True
d) False, False

Answer: a
Clarification: The applications of Pascal law in daily life is that it is used in hydraulic pumps and hydraulic press. It is also commonly used in in braking system in the vehicles where a fluid called brake fluid is used to transmit the pressure from the brake pedal to the all the vehicle wheels.

7. Who is the father of fluid mechanics?
a) Stephen Prokofievitch Timoshenko
b) Ludwig Prandtl
c) Singh Kapany
d) Samuel Colville Lind

Answer: b
Clarification: Ludwig Prandtl is called as the father of fluid mechanics. Stephen Prokofievitch Timoshenko is father of engineering mechanics. Singh Kapany is the father of fiber optics. Samuel Colville Lind is father of chemical kinetics.

8. What are applications of fluid statics?
a) Barometers, anemometer
b) Manometers, anemometer
c) Manometers, hygrometer
d) Manometer, barometers

Answer: d
Clarification: Manometer, barometers are used in measuring the pressure of the fluid based on the fluid state mechanism. Anemometer is used in measuring the wind speed and also the direction of the wind. Hygrometer is used to measure the humidity.

9. Fluid in static condition has shear stress.
a) True
b) False

Answer: b
Clarification: A fluid in static condition has no shear stress. The shear stress is known as force per unit area that is acting parallel to the inconsiderable surface element. It is mainly caused by the friction between fluid molecules due to viscosity of the fluid.

10. What causes the turbulence in fluid flow?
a) Kinetic energy
b) Pressure
c) Force
d) Potential energy

Answer: a
Clarification: During the flow of the fluid, the excessive kinetic energy that is present in the fluid causes the turbulence which overpowers the resistance of fluid. The turbulence is reduced by reducing Reynolds number.