Engineering Questions with Answers - Multiple Choice Questions
Distillation Design MCQ’s – Vapour Liquid Equilibrium
1 - Question
Which of the following shows the correct Gibbs phase rule equation?
a) F=C-P+2
b) P=C+P
c) C=F-P+2
d) C=P-F
View Answer
Answer: a
Explanation: According to Gibb’s F=C-P+2 for any system, where F is degree of freedom, C is number of components and P is the number of phases.
2 - Question
The higher the concentration of volatile species, the distillation
a) The higher the rate of liquid flow
b) The lower the rate of Separation
c) The higher the rate of separation
d) Cannot be specified
View Answer
Answer: c
Explanation: Volatility is directly proportional to the ease of separation (α) while it is inversely proportional to difficulty of separation.
3 - Question
VLE data once obtained is represented on which scale?
a) Binary Scale (0<x<1)
b) Pressure Scales (0<Pa<1)
c) Temperature Ranges (T1<x<T2)
d) Not specific
View Answer
Answer: a
Explanation: Binary scales are most suitable as they represent mole fractions of the both species x* and y* at all conditions.
4 - Question
When the boiling temperature is plotted against the liquid composition, then it is called
a) Cooling Curve
b) Heating Curve
c) Bubble point curve
d) Volatility Phase Diagram
View Answer
Answer: c
Explanation: The (T-x) curve is called as Bubble point Curve, Where T is boiling temperature and x is the mole fraction of the liquid.
5 - Question
When the temperature is plotted against the equilibrium vapor, then it is called
a) Condensing Curve
b) Dew Point curve
c) Equilibrium Curve
d) Bubble Curve
View Answer
Answer: b
Explanation: The (T-y*) curve is called as Dew point Curve, Where T is boiling temperature, and y is the equilibrium moles of the gaseous components.
6 - Question
The K value can be expressed as
a) y/x
b) yi/x
c) x/y
d) yi/xi
View Answer
Answer: d
Explanation: The ratio of mole fraction of components in vapor and liquid phase is called as K value.
7 - Question
The Relative Volatility of components i and j can be defined as
a) Ki/Kj
b) K/Kj
c) yi/y
d) xi/x
View Answer
Answer: a
Explanation: The ratio of K values is defined as the relative volatility, Where Ki is the gaseous components and Kj is the fluid components
8 - Question
Given that αAB=2.0, Then equilibrium ratio of B is KB=0.7, Estimate αBA ?
a) 0.9
b) 0.65
c) 0.5
d) 0.6
View Answer
Answer: c
Explanation: As α=KB/KA, 2.0= 0.7/KA, KA = 0.35 and αAB =KA/KB =0.35/0.7 = 0.5.
9 - Question
Which system can be said as an Ideal system that obeys?
a) Henrys Law
b) Daltons Law
c) Phase Rule
d) Cremer’s rule
View Answer
Answer: d
Explanation: The system that obeys Henry’s and Dalton’s Law is called an ideal system, as they are derived from the ideal gas relation PV=Nrt.
10 - Question
Which of the below is the Dalton’s Law?
a) pi = yi/P
b) x = yi/ pi
c) pi = yi/x
d) pi = xi/y
View Answer
Answer: a
Explanation: According to Dalton’s law the partial pressure of component is solution is equal to product of its mole fraction and vapor pressure of pure components.