Engineering Questions with Answers - Multiple Choice Questions
Food Engineering MCQ’s – Unit Operations – Mixing-2
1 - Question
Which of the following is NOT an application of mixing solids in the food industry?
a) Biscuit/bakery making
b) Poultry and cattle feed
c) Chips and snacks industry
d) None of the mentioned
View Answer
Explanation: All the mentioned are applications of mixing in the food industry.
2 - Question
Which of the following is NOT a mixing involved with fluids in the food industry?
a) Soup powders
b) Carbonated drinks
c) Oxygen transfer in fermentation broths
d) None of the mentioned
View Answer
Explanation: Soup powders involve mixing of solids. Carbonated drinks involve mixing of gas with a liquid. Oxygen transfer in fermentation broths involves mixing of gas in liquid again.
3 - Question
Which of the following does NOT include power required for mixing by an impeller?
a) Rheological nature of the fluid
b) Friction in the motor
c) Speed, nature and type of the impeller
d) None of the mentioned
View Answer
Explanation: Friction in the motor does NOT include power required for mixing by an impeller.
4 - Question
Power required for a gassed system is more than that required for an ungassed system.
a) True
b) False
View Answer
Explanation: Power required for an ungassed system is more than that required for a gassed system. This is because when gas is sent into the fluid via a nozzle, the density of the fluid near the impeller decreases and hence the power required for it is lesser.
5 - Question
Statement 1: Froude number relates the gravitational effect which is important when the liquid is agitated by an impeller. Statement 2: When NRe,i < 300, NFr is ineffective.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Froude number relates the gravitational effect which is important when the liquid is agitated by an impeller. When NRe,i < 300, NFr is ineffective.
6 - Question
With respect to the relationship between the power number and the impeller Reynolds’s number, which amongst the following statements is true?
a) In the turbulent region, the NRe,i has no impact over NPo
b) In the transient region, the NRe,i has no impact over NPo
c) In the laminar region, the NPo continually falls as NRe,i increases
d) None of the mentioned
View Answer
Explanation: In the turbulent region, the NRe,i, impeller Reynolds’s number, has no impact over NPo, power number.
7 - Question
Statement 1: In the transient zone, the power input depends on the density and viscosity of the fluid.
Statement 2: In the laminar zone, the power input depends on the density only. It is independent of the viscosity of the fluid.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: In the laminar zone, the power input depends on the viscosity only. It is independent of the density of the fluid.
8 - Question
Statement 1: For non-Newtonian fluids, another term called apparent viscosity is used as their viscosity changes with the change in the shear rate.
Statement 2: For non-Newtonian fluids, between the transition region, the power number for non-Newtonian fluids is slightly higher than that for Newtonian fluids.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: For non-Newtonian fluids, between the transition region, the power number for non-Newtonian fluids is slightly lower than that for Newtonian fluids.
9 - Question
Statement 1: Where Pg is power for a gassed system and Po is power for an ungassed system, Pg/Po is _____
Statement 2: Na stands for _____
a) < 1, aeration number
b) > 1, aeration number
c) < 1, consistency index
d) > 1, consistency index
View Answer
Explanation: Power required for an ungassed system Po is more than that required for a gassed system Pg. This is because when gas is sent into the fluid via a nozzle, the density of the fluid near the impeller decreases and hence the power required for it is lesser.
10 - Question
Statement 1: Flat blade/curve blade/arrow head/vaned disc turbines are generally used for gas-liquid mixing.
Statement 2: Helical screw/ribbon mixer/gate anchor are generally used for solid-solid mixing.
a) True, False
b) True, True
c) False, False
d) False, True
View Answer
Explanation: Flat blade/curve blade/arrow head/vaned disc turbines are generally used for gas-liquid mixing. Helical screw/ribbon mixer/gate anchor are generally used for solid-solid mixing.
11 - Question
Which of the following is true with respect to Carbonation?
a) Gas-liquid mixing
b) Helps improve storage life
c) Increased pressure
d) All of the mentioned
View Answer
Explanation: All of the mentioned are true with respect to Carbonation.
12 - Question
With respect to dipping oil emulsions, which of the following is true?
a) Used for easy dehydration of food
b) Gives a thin layer of coating on the fruit berries
c) Dipping oil made from an emulsion by mixing of fatty esters with some amount of aqueous potassium carbonate solutions by high speed impellers
d) All of the mentioned
View Answer
Explanation: All of the mentioned is true about dipping oil emulsions.