Engineering Questions with Answers - Multiple Choice Questions

# Separation Processes MCQ’s – Rate Based Method for Packed Columns

1 - Question

Packed columns are better analyzed by:
a) Mass transfer coefficients
b) Equilibrium stage methods
c) Graphical methods
d) Algebraical methods
View Answer Answer: a
Explanation: Packed columns are better analyzed by mass transfer coefficients.

2 - Question

What is the formula for HETP or HETS?
a) HETP = l T *N T
b) HETP = l T-N T
c) HETP = l T /NT
d) HETP = lT+NT
View Answer Answer: c
Explanation: The formula for HETP is HETP = lT/NT where lT is the packed height length and the N T is the number of equilibrium stages

3 - Question

At the interface of liquid and vapor, which interface exists?
a) Chemical
b) Physical
c) Thermal
d) No equilibrium exists
View Answer Answer: b
Explanation: At the interface of liquid and vapor, a physical equilibrium exists.

4 - Question

Which of the following is the correct illustration of rate of mass transfer?
a) r= ky a(y-y 1 ) =kx a(x-x 1 )
b) r= ky a(y 1 -y) =kx a(x 1 -x)
c) r= ky a(y-y 1 ) =kx a(x 1 -x)
d) r= a(y-y 1 ) =a(x 1 -x)
View Answer Answer: c
Explanation: r= k y a(y-y 1 ) =k xa(x 1 -x) is the correct illustration for rate of adsorption where kya and k x a are volumetric mass transfer coefficients.

5 - Question

Which of the following is the correct representation of overall mass transfer coefficient?
a) 1/Ky a = 1/ky a +K/Kx a
b) 1/Ky a = 1/ky a +K/Ky a
c) 1/Ky a = 1/ky a +1/KKx a
d) Ky a = 1/ky a +K/Kx a
View Answer Answer: a
Explanation: The correct representation of overall mass transfer coefficient is 1/K y a = 1/k y a +K/K x a, where K y is the overall mass transfer coefficient obtained from slope=point form

6 - Question

What is the overall height of gas transfer unit if the volume is 1000m 3 and the overall gas phase coefficient is 2.6 and the inside cross sectional area is 20m 2 .
a) 12m
b) 13.6m
c) 18.9m
d) 19.2m
View Answer Answer: d
Explanation: HOG = V/ky aS, hence HOG= 1000/2.6*20=19.2.

7 - Question

What is the overall height of gas transfer unit if the volume is 780m 3 and the overall gas phase coefficient is 4.2 and the inside cross sectional area is 45m 2 .
a) 4.1m
b) 7.2m
c) 10.4m
d) 19.2m
View Answer Answer: a
Explanation: HOG = V/ky aS, hence HOG= 780/4.2*45=4.1.

8 - Question

What is the overall height of gas transfer unit if the volume is 489m 3 and the overall gas phase coefficient is 1.2 and the inside cross sectional area is 22m 2 .
a) 12m
b) 13.6m
c) 18.5m
d) 19.2m
View Answer Answer: c
Explanation: HOG = V/ky aS, hence HOG= 489/1.2*22=18.5.

9 - Question

What is the packed height length is HETP is 3ft and the number of equilibrium stages is
a) 0.75
b) 1.33
c) 12
d) 16
View Answer Answer: c
Explanation: HETP =lT /NT , hence lT =4*3=12.

10 - Question

What is the packed height length is HETP is 3.8ft and the number of equilibrium stages is
a) 0.76
b) 1.3157
c) 12
d) 19
View Answer Answer: c
Explanation: HETP =lT /NT , hence lT =3.8*5=19.

11 - Question

What is the packed height length is HETP is 6ft and the number of equilibrium stages is
a) 0.76
b) 1.3157
c) 30
d) 19
View Answer Answer: c
Explanation: HETP =lT /NT , hence lT =6*5=30.

12 - Question

What is the packed height length is HETP is 4.2ft and the number of equilibrium stages is
a) 0.76
b) 8.4
c) 12
d) 19
View Answer Answer: b
Explanation: HETP =lT /NT , hence lT =4.2*2=8.4.