Multiple choice question for engineering
Set 1
1. Which of the following is also called Rating method?
a) McCabe Thiele
b) Ponchan Savarit
c) Thiele Geddes
d) Homotomy
Answer
Answer: c [Reason:] Thiele Geddes is also called as rating method, McCabe Thiele is called tray analysis method and Ponchan Savarit as enthalpy method.
2. In Thiele Geddes method, which of the following are calculated?
a) Vapor and liquid compositions
b) Input and output fees rates
c) Reflux ratio
d) Boil up
Answer
Answer: a [Reason:] Vapor and liquid compositions are calculated In Thiele Geddes method, while reflux ratio in McCabe Thiele method.
3. Which method is the inverse of Thiele Geddes Method?
a) Lewis Matheson
b) Ponchan Savarit
c) McCabe Thiele
d) Homotomy
Answer
Answer: a [Reason:] Lewis Matheson is the inverse of Thiele Geddes method, while other listed methods are completely different from each other and all are used to calculate number of trays.
4. Lewis Matheson method can be adjusted, for fixed number of
a) Trays
b) Stages
c) Columns
d) Sections
Answer
Answer: b [Reason:] Lewis Matheson method can be adjusted for fixed number of Stages instead of reflux ratio fixed.
5. Tj is assigned as the
a) Stage temperature
b) Boiler temperature
c) Condenser temperature
d) Components temperature
Answer
Answer: d [Reason:] Tj is assigned as the Stage temperature, While TC and TB are assigned as condenser and boiler temperature.
6. The value of K is independent of
a) Composition
b) Feed ratio
c) Volatility
d) Reflux
Answer
Answer: a [Reason:] As per the relation the value of K is given as the function of KV = f (pure liquid)/f (pure vapor).
7. User provided internal flows are generally for
a) Reflux in high purity
b) Overhead liquid products
c) Narrow building columns
d) NOR relation
Answer
Answer: d [Reason:] User provided internal flows are generally for Reflux in high purity, overhead liquid products and Narrow building columns also called as NOR relation.
8. For accurate Reflux, estimate
a) Reflux of high purity is used
b) Narrow boiling is used
c) Super fractionators are used
d) Final temperature is used
Answer
Answer: b [Reason:] For accurate Reflux estimate, narrow boiling is necessary, where separation is required the reflux of high priority is used.
9. Azeotropic composition is?
a) y*>x
b) y*<x
c) y*=x
d) x+y* = 1
Answer
Answer: c [Reason:] Azeotropic composition is y*=x, whereas the x+y* = 1 gives the actual mole balance of gas and liquid at equilibrium.
10. Molecular Distillation is
a) For heat sensitive materials
b) Very low pressure distillation
c) High low pressure distillation
d) Purge pressure
Answer
Answer: b [Reason:] Molecular Distillation is done for very low pressure distillation operations, while batch distillation occurs at high pressure and temperatures.
Set 2
1. The overall Material balance, is given as
a) F = D+B
b) D =F +B
c) F = D+B
d) F=B-D
Answer
Answer: a [Reason:] F = B+D where F=Feed moles
D=Distillates
B= Bottoms moles.
2. The material Balance around a condenser, is given as
a) F = D+B
b) F = D+B
c) V = L+D
d) L= V + D
Answer
Answer: c [Reason:] V = L+D
V= Vapor from column
L= liquid returning to column.
3. For a batch distillation process
a) –ydV = d(xW)
b) –xdV = d(xW)
c) -xW =d(yV)
d)- yW =d(xV)
Answer
Answer: a [Reason:] –ydV = d(xW) where dV= vapor rate, moles/h
W=total moles in still.
4) The below equation, holds well for?
a) Flash distillation
b) Simple distillation
c) Multicomponent distillation
d) Final distillation
Answer
Answer: b [Reason:] This holds for simple distillation Where Wf=moles in the still and W0=moles originally charged.
5. 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) 18.0
Answer
Answer: c [Reason:] As In WF⁄100 = -1.79
So WF = 16.7.
6. Find α. If Xd=0.517 and Xw=0.3
a) 1.3
b) 2.5
c) 5.6
d) 3.4
Answer
Answer: b [Reason:] As α = Xd(1-Xw)/ Xw(1- Xd) using values we have 0.517(1-0.3)/0.3(1-0.517) = 2.5.
7. Calculate F? If D=4.61 and W=5.39
a) 7.8
b) 10
c) 9
d) 1.34
Answer
Answer: b [Reason:] As F = D +W = 4.61+5.39 = 10.
8. Calculate the enthalpy HF? If Cp= 0.825, W=32 and Tref=15C, at room temperature
a) 119 kcal/kmol
b) 78 kcal/kmol
c) 700 kcal/kmol
d) 70 kcal/kmol
Answer
Answer: a [Reason:] As Hf = (0.825) (32) (25-15) =119 kcal/kmol.
9. Batch distillation is also called as?
a) Flash distillation
b) Rayleigh’s Criteria
c) Thompson Distillation
d) Crane Distillation
Answer
Answer: b [Reason:] Batch distillation is also called as Rayleigh’s Criteria. As he invented it early 19th century, in this feed composition varies from time to time.
10) Flash distillation is called as?
A) Final distillation
B) Equilibrium distillation
C) Growth distillation
D) Full distillation
Answer
Answer: b [Reason:] Flash distillation is called as Equilibrium distillation because the volatility is the basis of the separation and will make components differ in mixture.
Set 3
1. The SR Method is suitable for
a) Absorbers and strippers
b) Distillation and absorber
c) Any equipment’s
d) High pressure equipment’s
Answer
Answer: b [Reason:] The SR Method is suitable for Absorbers and strippers, whereas NR method is widely used for calculation of distillation and High pressure equipment’s.
2. Absorbers have a rich bottom of
a) Solid
b) Liquid
c) Gas
d) Semi solid
Answer
Answer: c [Reason:] Absorbers have a rich bottom feed stage of Gas, as absorption occurs at interfacial levels the gas diffuse into the liquid surfaces and bottom is rich of gas.
3. Absorbers have a lean end of
a) Solute
b) Substrate
c) Mother liquor
d) Extract liquid
Answer
Answer: d [Reason:] Absorbers have a lean end of oil top feed stage and a forward end of the liquid at the bottom feed stage.
4. Gas rich feed is represented as
a) VN+1
b) YN+1
c) XN+1
d) XN
Answer
Answer: a [Reason:] Gas rich feed is represented, as VN+1 and the liquid rich phases are represented as LN+1 for all cases listed.
5. The number of independent functions are equal to
a) Number of Trays
b) Number of Stages
c) Number of species
d) Number of Feeds
Answer
Answer: b [Reason:] as Fi = [E1 E2 E3…..EN] independent functions are equal to number of Stages, it has no relation with the number of trays and feed they are totally independent.
6. The independent variables of NR Method are related as Xk
a) [E1 E2 E3 …. EN-1 EN].
b) [T1 T2 T3 …. TN-1 TN].
c) [S1 S2 S3 …. SN-1 SN].
d) [K1 K2 K3 …. KN-1 KN].
Answer
Answer: b [Reason:] The independent variables of NR Method are related as Xk= [T1 T2 T3 …. TN-1 TN], here T represents the operating temperature of the column.
7. The SR Method requires the
a) Total flow rate
b) Total heat
c) Total Feed
d) Total trays
Answer
Answer: a [Reason:] The SR Method requires the total flow rate at all locations being specified, while NR method only requires the initial conditions to be specified.
8. 
represents the Value of
a) Sum of feeds
b) Liquid flow rates
c) Gas flow rates
d) Vapor flow rates
Answer
Answer: c [Reason:] The equation represents, the summation of gas flow rates and C represents the number of components that vary from 1 to c.
9. 
represents the Value of
a) Sum of feeds
b) Liquid flow rates
c) Gas flow rates
d) Components
Answer
Answer: b [Reason:] The equation represents the summation of Liquid flow rates, here l represent the species with L compositions of i and j.
10. The SR Method can be used in
a) FLOWTRAN
b) ASPEN
c) ChemCAD
d) ACS
Answer
Answer: d [Reason:] All simulation software’s uses the same algorithm as directed by ACS i.e. American Chemical Society, other listed are various best simulation software’s available.
Set 4
1. Jafarey, Dougles and Mcavoy Equation is capable of predicting
a) Column performance
b) Column feed rate
c) Column design
d) Column diameter
Answer
Answer: a [Reason:] Jafarey, Dougles and Mcavoy Equation is capable of predicting Column performance and control of disturbances.
2. The term PLK stands for
a) Primary left key
b) Pseudo Left key
c) Pseudo light key
d) Pressure light key
Answer
Answer: b [Reason:] The term PLK stands for Pseudo Left key, which indicated the components which are heavy key and are separated at left side.
3. PHK and PLK are also applied in
a) Hengstebeck’s equation
b) Fenske’s equation
c) Gilliland equation
d) Homotomy equation
Answer
Answer: a [Reason:] PHK and PLK are also applied in Hengstebeck’s method, while Fenske’s equation uses the relative volatility.
4. Jafarey Equation is an analytical closed form formula, to calculate
a) Reflux ratio
b) Number of trays
c) Number of stages
d) Number of feeds
Answer
Answer: b [Reason:] Jaffrey Equation is an analytical closed form formula to calculate Number of trays simplifying smoker’s equation.
5. In Jafarey Equation, N is predicted with an error of
a) ± 2 to 3
b) ± 1 to 2
c) ± 6 to 7
d) Can’t be specified
Answer
Answer: a [Reason:] In Jafarey Equation N is predicted with an error of ± 2 to 3 stages, this is an ideal error with respect to human and conservative errors that occur.
6. PHK stands for
a) Pre Heavy key
b) Pseudo Heavy key
c) Primary Heavy key
d) Pressure Heavy key
Answer
Answer: b [Reason:] PHK stands for Pseudo Heavy key representing the bottom end products which are removed at the bottom of column.
7. Dougles equation is useful for
a) Binary separations
b) Multicomponent separations
c) Tertiary Separations
d) Cant’ be specified
Answer
Answer: b [Reason:] Dougles equation is useful for multicomponent separations extended form of smoker’s equation.
8. Calculate ln S? If XLK=0.95 and XHK = 0.05 and XL= 0.90 and XH= 0.10, then
a) 6.77
b) 5.142
c) 7.898
d) Can’t be calculated
Answer
Answer: b [Reason:] as ln (0.95/0.05) (0.90/0.10) = 5.142.
9. Solve the following equation 0.3089R2 – 0.4033R – 0.1242=0?
a) 2.45
b) 1.31
c) 8.9
d) 7.8
Answer
Answer: b [Reason:] Using quadratic formula f(x) =0.3089R2 – 0.4033R – 0.1242, and at f (1.31) = 0 we can conclude and thus R=1.31.
10. The overall column efficiency is defined as
a) Nthoretical/Nactual
b) Nthoretical*Nactual
c) Nthoretical=Nactual
d) Nactual + 1
Answer
Answer: a [Reason:] The overall column efficiency is defined as Eoverall = Nthoretical/Nactual, whereas Nactual + 1 gives the real number of trays in a column.
Set 5
1. An ideal distillation stage is the one that
a) Operates at steady state
b) Operates at High temperature
c) Operates at Low pressure
d) Operates at high pressure
Answer
Answer: a [Reason:] An ideal distillation stage operates at steady state has liquid product and vapor product, i.e. Liquid rate equals the gas flow rate.
2. When heat is supplied to bottom of liquid stage to vaporize a portion it is called
a) Condensing
b) Boil up
c) Cooling
d) Desalting
Answer
Answer: b [Reason:] Such operations used in stripping section called as Boil up, the boiler is used as a heat exchanger to reheat the condensed liquid.
3. When Cooling is applied to condense a part of overhead product it is called
a) Reflux
b) Dew point
c) Boil Up
d) Relative BP
Answer
Answer: a [Reason:] Such operations is called as Rectifying stages and called Reflux, It is also called the ratio of distillate and liquid flow rate.
4. When rectifying and stripping both are combined in single stage process this is
a) Differentiation
b) Fractionation
c) Recycle
d) Purging
Answer
Answer: b [Reason:] Such is an operation is also called Fractional Distillation, The moles of the components reduce with respect to time in this operation.
5. Minimum number of trays can be calculated using
a) Bernoulli’s Eon
b) Henry’s Law
c) Fenske’s Equation
d) Homotomy Equation
Answer
Answer: c [Reason:] Minimum number of trays can be easily calculated using Fenske’s equation with use of relative volatility.
6. The external reflux ratio can be defined as
a) L0/D
b) D/L
c) D0/L
d) V/L
Answer
Answer: d [Reason:] The reflux ratio is defined as the ratio of liquid flow rate and distilled flow rate, also this is called as the slope of rectifying line.
7. The boil up ratio can be defined as ratio of
a) V/L
b) D/V
c) V/W
d) L/W
Answer
Answer: c [Reason:] Boil up ratio is the ratio of vapor leaving the rebuilder to liquid at bottom product, also it is defined as the slope of stripping line.
8. Optimum reflux ratio ranges between
a) 2 to 5
b) 2 to 3
c) 1.0 to 1 .5
d) 1.0 to 2.5
Answer
Answer: c [Reason:] Best optimum reflux is between ranges. 1.0<R<1.5, as it is very close to unity the optimum conditions are best condition to operate.
9. If stages are fixed, then Reflux ratio
a) Decreases
b) Increases
c) Equates to 0
d) Approaches infinity.
Answer
Answer: b [Reason:] The stages and the reflux ratio are directly proportional, while when it approaches to 0 the distillate is not withdrawn and if infinite all feed is withdrawn.
10. If reflux increases, then the cost of operation
a) First increases then decreases
b) Goes on increasing
c) Approaches infinity
d) First decreases then increases
Answer
Answer: a [Reason:] The reflux ratio follows an exponential relation with cost, cost grows exponentially as the reflux increases and can cause increase in cost.
