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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

1.

Which one of the following is a constant reflux process?(a) Flash distillation(b) Simple distillation(c) Multicomponent distillation(d) Final distillationI have been asked this question in homework.My doubt is from Constant Reflux Ratio in chapter Batch Distillation of Distillation Design

Answer»

Correct ANSWER is (b) Simple distillation

For EXPLANATION I would say: Simple or BATCH distillation is WORKING on the CONSTANT reflux in such a distillation compositions continuously vary with time.
Discussion
2.

The Antoine equation is given as(a) ln VP = B –A/CT(b) ln VP =A – B/T(c) ln VP = B – A/T(d) ln VP = B -CAI got this question during an interview for a job.I want to ask this question from Constant Reflux Ratio topic in division Batch Distillation of Distillation Design

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Right choice is (b) ln VP =A – B/T

To explain: The ANTOINE EQUATION is ln VP =A – B/T where A, B and C are constants and VP is the VAPOR pressure.
Discussion
3.

As the distillation proceeds, the L/V ratio(a) Constant(b) Decreases(c) Increases(d) VanishesI have been asked this question by my college professor while I was bunking the class.The query is from Constant Reflux Ratio topic in division Batch Distillation of Distillation Design

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Right CHOICE is (c) Increases

The explanation is: The DISTILLATION and the L/V ratio are directly PROPORTIONAL and thus as distillation PROCEEDS L/V Increases.
Discussion
4.

Calculate F? If D=4.61 and W=5.39(a) 7.8(b) 10(c) 9(d) 1.34The question was asked in examination.The doubt is from Simple Distillation in portion Batch Distillation of Distillation Design

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Right ANSWER is (b) 10

Explanation: As F = D +W = 4.61+5.39 = 10.
Discussion
5.

The material Balance around a condenser, is given as(a) F = D+B(b) F = D+B(c) V = L+D(d) L= V + DI got this question in an interview.This question is from Simple Distillation in portion Batch Distillation of Distillation Design

Answer»

Correct answer is (c) V = L+D

Easiest explanation: V = L+D

V= VAPOR from COLUMN

L= LIQUID RETURNING to column.
Discussion
6.

If the area of the column is 3.61 m^2 and the initial and final distilled moles are 0.95 and 0.50 with Withdrawal of 100 moles, then V is?(a) 162(b) 456(c) 78(d) 45I had been asked this question during an internship interview.Query is from Constant Reflux Ratio in chapter Batch Distillation of Distillation Design

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Right ANSWER is (a) 162

Easiest EXPLANATION: As V= W0 (Xd – X0) (AREA) = 100 (0.95-0.50)3.61 = 162 moles.
Discussion
7.

For a batch distillation process(a) –ydV = d(xW)(b) –xdV = d(xW)(c) -xW =d(yV)(d) - yW =d(xV)This question was addressed to me by my school teacher while I was bunking the class.The origin of the question is Simple Distillation topic in portion Batch Distillation of Distillation Design

Answer» RIGHT option is (a) –ydV = d(XW)

Explanation: –ydV = d(xW) where DV= VAPOR rate, moles/h

W=total moles in still.
Discussion
8.

Calculate the enthalpy HF? If Cp= 0.825, W=32 and Tref=15^C, at room temperature(a) 119 kcal/kmol(b) 78 kcal/kmol(c) 700 kcal/kmol(d) 70 kcal/kmolThis question was posed to me by my college professor while I was bunking the class.This interesting question is from Simple Distillation in portion Batch Distillation of Distillation Design

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The CORRECT OPTION is (a) 119 kcal/kmol

Easy EXPLANATION: As HF = (0.825) (32) (25-15) =119 kcal/kmol.
Discussion
9.

If the integral part is given as -1.79 and still has 100 moles originally charged. Find the WF?(a) 15.8(b) 12.9(c) 16.7(d) 18.0The question was posed to me in an online interview.My question comes from Simple Distillation topic in division Batch Distillation of Distillation Design

Answer»

Correct OPTION is (c) 16.7

The BEST explanation: As In ^WF⁄100 = -1.79

So WF = 16.7.
Discussion
10.

The Ract can be taken, as(a) 1.3Rmin(b) 1.6 Rmin(c) 2.0 Rmin(d) 3.0 RminI got this question in an online interview.I'd like to ask this question from Constant Reflux Ratio in section Batch Distillation of Distillation Design

Answer» CORRECT answer is (C) 2.0 Rmin

For explanation: For a particulate separation the ACTUAL reflux ratio is TAKEN as to be TWICE the actual reflux ratio i.e. Rmin.
Discussion
11.

The initial mole Yint fraction of gas, can be obtained by(a) Xd/R+1(b) –dw=dD(c) – dy=dZ(d) R+1I have been asked this question in a job interview.I want to ask this question from Constant Reflux Ratio in section Batch Distillation of Distillation Design

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Correct ANSWER is (a) Xd/R+1

Easy EXPLANATION: Yint FRACTION of GAS can be OBTAINED by Xd/R+1, Where Yint=value of y at x =0.
Discussion
12.

Batch distillation under constant reflux can be analyzed?(a) –dw=dD(b) dv=-dx(c) – dy=dZ(d) dX=dyThis question was posed to me by my school teacher while I was bunking the class.I'm obligated to ask this question of Constant Reflux Ratio topic in section Batch Distillation of Distillation Design

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The correct option is (a) –dw=dD

The explanation is: –dw = dD where,W= STILL MOLES and D= moles of distillate.
Discussion
13.

Batch distillation is also called as?(a) Flash distillation(b) Rayleigh’s Criteria(c) Thompson Distillation(d) Crane DistillationThe question was posed to me during a job interview.I'm obligated to ask this question of Simple Distillation topic in division Batch Distillation of Distillation Design

Answer» RIGHT ANSWER is (b) RAYLEIGH’s Criteria

The best explanation: Batch distillation is also CALLED as Rayleigh’s Criteria. As he invented it early 19^th century, in this feed composition varies from time to time.
Discussion
14.

The overall Material balance, is given as(a) F = D+B(b) D =F +B(c) F = D+B(d) F=B-DThe question was asked in an internship interview.The above asked question is from Simple Distillation in section Batch Distillation of Distillation Design

Answer» RIGHT CHOICE is (a) F = D+B

The best explanation: F = B+D where F=Feed moles

D=Distillates

B= Bottoms moles.
Discussion
15.

Calculate V? If D = 52.2 moles and R is 1.64(a) 138 moles(b) 35 moles(c) 450 moles(d) 46 molesI got this question during an interview for a job.I need to ask this question from Constant Reflux Ratio topic in section Batch Distillation of Distillation Design

Answer» RIGHT CHOICE is (a) 138 MOLES

Explanation: As the V = D(R+1) = 52.2 (1.64+1) = 138 moles.
Discussion
16.

Find R? If Xd = 0.98 and Yi =0.647(a) 0.633(b) 0.589(c) 0.515(d) 0.25I have been asked this question in semester exam.The query is from Constant Reflux Ratio topic in section Batch Distillation of Distillation Design

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The CORRECT choice is (C) 0.515

The best explanation: As R = XD/ Yi – 1 = 0.98/0.647 – 1 = 0.515.
Discussion
17.

Find α. If Xd=0.517 and Xw=0.3(a) 1.3(b) 2.5(c) 5.6(d) 3.4I have been asked this question by my school teacher while I was bunking the class.My question is based upon Simple Distillation topic in division Batch Distillation of Distillation Design

Answer» CORRECT choice is (B) 2.5

To explain I would say: As α = Xd(1-Xw)/ Xw(1- Xd) USING VALUES we have 0.517(1-0.3)/0.3(1-0.517) = 2.5.
Discussion