Engineering Questions with Answers - Multiple Choice Questions

# Food Engineering MCQ’s – Unit Operations – Equilibrium Stage Operations-2

1 - Question

Which of the following is a process/method to enhance the amount of pure distillate?
a) Rectification
b) Stripping
c) Re-fluxing
d) All of the mentioned
Explanation: Rectification, Stripping and Re-fluxing are all processes/methods to enhance the amount of pure distillate.

2 - Question

In re-fluxing, the re-flux ratio needs to a minimum.
a) True
b) False
Explanation: The re-flux ratio being minimum means that an infinite number of plates are required and vice-versa. Hence the re-flux ratio needs to be more than the minimum.

3 - Question

The feed line tells us that a particular feed A is at a sub-cooled liquid. Which of the following explains the above statement?
a) The liquid is at its boiling point
b) None of the mentioned
c) A liquid below its boiling temperature
d) The liquid is a mixture of boiling and some vapors
Explanation: A liquid below its boiling temperature means it is sub-cooled.

4 - Question

Statement 1: Bubble point means the feed is at saturated vapor.
Statement 2: Dew point means the feed is at boiling point.
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: Dew point means the feed is at saturated vapor. Bubble point means the feed is at boiling point.

5 - Question

When q=(Heat required to convert one mole of feed to saturated vapor)/(Molar heat of vaporization of feed) Statement 1: q<1 means the liquid is sub-cooled.
Statement 2: q<0 means the liquid is super heated vapor.
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: q>1 means the liquid is sub-cooled. Or q<1 means the liquid is a mixture of liquid and vapor. q<0 means the liquid is super heated vapor.

6 - Question

When q=(Heat required to convert one mole of feed to saturated vapor)/(Molar heat of vaporization of feed) Statement 1: q<1 means the slope is a horizontal line.
Statement 2: q<1 means the slope is a vertical line.
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: q=0 means the slope is a horizontal line. q=1 means the slope is a vertical line. Or q<1 means the slope is negative.

7 - Question

With respect to ammonia-water system –
Statement 1: Limiting ratio is when the __(1)___ will meet __(2)__
Statement 2: When the flow rate of liquid is high, the distance between (1) and (2) decreases.
a) Operating line will meet Equilibrium curve, false
b) Equilibrium curve will meet Equilibrium line, true
c) Operating line will meet Equilibrium line, true
d) All of the mentioned
Explanation: Limiting ratio is when the Operating line will meet equilibrium curve. Gas liquid ratio = L/V. When the flow rate of liquid is high, the distance between operating line and equilibrium curve increases.

8 - Question

∫y0ybdy/(y-y*) gives you _____
a) Height of one transfer unit
b) Height of the entire column
c) Number of transfer units in the column
d) None of the mentioned
Explanation: ∫y0ybdy/(y-y*) gives you number of transfer units in the column.

9 - Question

Statement 1: Hydrogenation of fats involves liquid-gas phases only.
Statement 2: Hydrogenation of fats is known as slurry reactor system.
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: Hydrogenation of fats involves solid-liquid-gas phases. Hydrogenation of fats is known as slurry reactor system.

10 - Question

Statement 1: Vapour-liquid-Equilibria is related to by a simple expression of Raoult’s law.
Statement 2: Raoult’s law is applicable to real gases.
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: Vapour-liquid-Equilibria is related to by a simple expression of Raoult’s law. Raoult’s law is applicable to ideal gases.

11 - Question

Raoult’s law is when mole fraction approaches zero and Henry’s law is applicable when concentration approaches zero.
a) True
b) False
Explanation: Raoult’s law is when mole fraction approaches zero and Henry’s law is applicable when concentration approaches zero. Raoult’s law is for pure components and Henry’s law is applicable to dilute solution.

12 - Question

Ethanol-water mixture is a popular example of a mixture exhibiting the typical VLE curve.
a) True
b) False
Explanation: Ethanol-water mixture is a popular example of a mixture NOT exhibiting the typical VLE curve.

13 - Question

Statement 1: Boiling point concentration diagram plots y against x. (Mole fraction in gas and liquid phase respectively).
Statement 2: VLE curve plots y against x. (Mole fraction in gas and liquid phase respectively).
a) True, False
b) True, True
c) False, False
d) False, True
Explanation: Boiling point concentration diagram plots temperature against x and y. VLE curve plots y against x.

14 - Question

Statement 1: Batch distillation is used for small capacity operations.
Statement 2: In food processing, batch distillation is used for desolventization.
a) True, False
b) True, True
c) False, False
d) False, True