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# Multiple choice question for engineering

## Set 1

1. What is fixed for a column of given diameter?
a) Feed rate
b) Boiling point
c) Molar vapor boilup rate
d) Molar flow rate

Answer: c [Reason:] The molar vapor boilup rate is fixed for a column of a given diameter.

2. For a batch rectifier, R=1, Boilup rate = 100mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 1 hr
b) 2 hr
c) 3 hr
d) 4 hr

Answer: a [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 1hr.

3. For a batch rectifier, R=2, Boilup rate = 50mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 1 hr
b) 2 hr
c) 3 hr
d) 4 hr

Answer: c [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 3hr.

4. For a batch rectifier, R=1, Boilup rate = 50mol/hr
Moles of liquid residue at start W0=70
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 0.6 hr
b) 0.8hr
c) 1 hr
d) 0.9 hr

Answer: b [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 0.8hr.

5. For a batch rectifier, R=1, Boilup rate = 100mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 80
Calculate time required for batch rectification.
a) 0.2 hr
b) 0.4hr
c) 0.6 hr
d) 0.8 hr

Answer: a [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 0.2hr.

6. For a batch rectifier, R=1, Boilup rate = 100mol/hr
Moles of liquid residue at start W0=200
Moles of liquid residue at end W= 100
Calculate time required for batch rectification.
a) 1 hr
b) 2 hr
c) 3 hr
d) 4 hr

Answer: b [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 2hr.

7. For a batch rectifier, R=4, Boilup rate = 100mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 1 hr
b) 2 hr
c) 2.5 hr
d) 3 hr

Answer: c [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 2.5hr.

8. For a batch rectifier, R=1, Boilup rate = 200mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 0.2 hr
b) 0.21 hr
c) 3 hr
d) 0.25 hr

Answer: d [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 0.25hr.

9. For a batch rectifier, R=1, Boilup rate = 20mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 3 hr
b) 4 hr
c) 5 hr
d) 6 hr

Answer: c [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 5hr.

10. For a batch rectifier, R=1, Boilup rate = 70mol/hr
Moles of liquid residue at start W0=100
Moles of liquid residue at end W= 50
Calculate time required for batch rectification.
a) 1.3 hr
b) 1.42 hr
c) 3 hr
d) 2.5 hr

Answer: b [Reason:] Since the time required for batch distillation is given by t= (R+1)/V*(Wo-Wt), t= 1.42hr.

## Set 2

1. In differential distillation, there is no ____________
a) Distillate
b) Reaction
c) Reflux
d) Vapors

Answer: c [Reason:] In differential distillation, there is no reflux.

2. What is the condition for Yd and xd for toatal condensation?
a) Yd greater than xd
b) Yd smaller than xd
c) Yd smaller than or equal to xd
d) Yd equal to xd

Answer: d [Reason:] For total condensation Yd=Xd.

3. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.6
Mole fraction in liquid at end X= 0.5
a) 0.2
b) 0.3
c) 0.4
d) 0.5

Answer: a [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.2.

4. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 800
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.5
Mole fraction in liquid at end X= 0.1
a) 0.2
b) 0.3
c) 1
d) 0.5

Answer: c [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 1.

5. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 2000
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.3
Mole fraction in liquid at end X= 0.4
a) 0.23
b) 0.34
c) 0.27
d) 0.56

Answer: c [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.27.

6. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.5
Mole fraction in liquid at end X= 0.2
a) 0.2
b) 0.66
c) 0.4
d) 0.8

Answer: d [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.8.

7. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.25
Mole fraction in liquid at end X= 0.1
a) 0.2
b) 0.3
c) 0.4
d) 0.5

Answer: c [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.4.

8. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 600
Mole fraction in liquid at start X0 = 0.6
Mole fraction in liquid at end X= 0.5
a) 0.2
b) 0.67
c) 0.44
d) 0.75

Answer: d [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.75.

9. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 500
Mole fraction in liquid at start X0 = 0.7
Mole fraction in liquid at end X= 0.4
a) 0.2
b) 1
c) 0.4
d) 0.5

Answer: b [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 1.

10. What is the mole fraction in instantaneous distillate if:
Moles of liquid in residue at start W0= 1000
Moles of liquid in residue at end W= 300
Mole fraction in liquid at start X0 = 0.6
Mole fraction in liquid at end X= 0.5
a) 0.26
b) 0.61
c) 0.64
d) 0.59

Answer: c [Reason:] XD = W0X0 –WX/W0-X, hence Xd= 0.64.

## Set 3

1. Which distillation is used to separate azeotropes and close boiling mixtures?
a) Extractive distillation
b) Salt distillation
c) Pressure-swing distillation
d) Reactive distillation

Answer: a [Reason:] Extractive distillation is used to separate azeotropes and close boiling mixtures.

2. If the feed is ______ boiling azeotrope the solvet enters the column with the feed.
a) Maximum
b) Minimum
c) Low
d) High

Answer: a [Reason:] If the feed is maximum boiling azeotrope the solvet enters the column with the feed.

3. Why is water the preferred solvent for separating acetone and methanol?
a) Because it does not form hydrogen bonding
b) Because it does not react with it
c) Because water is an universal solvent
d) Because water does not form binary or ternary azeotropes with acetone or methanol.

Answer: d [Reason:] Water is the preferred solvent for separating acetone and methanol because water does not form binary or ternary azeotropes with acetone or methanol.

4. What happens due to presence of appreciable water?
a) Phase activity coefficient of acetone increases and that of methanol decreases
b) Phase activity coefficient of acetone decreases and that of methanol increases
c) Phase activity coefficient of both methanol and acetone increases
d) Phase activity coefficient of both decreases

Answer: a [Reason:] Phase activity coefficient of acetone increases and that of methanol decreases due to presence of appreciable water.

5. What is the distillate and bottom in presence of appreciable water?
a) Distillate of methanol and bottoms of acetone
b) Distillate of acetone and bottoms of methanol
c) Distillate of both acetone and methanol
d) Bottoms of both acetone and methanol

Answer: b [Reason:] Due to presence of appreciable water, we get a distillate of acetone and bottoms of methanol.

6. What is the unfortunate point of extractive distillation?
a) Water has low boiling point
b) Water has high boiling point
c) Extractive distillation is costly
d) Extractive distillation is not efficient

Answer: a [Reason:] Water having a low boiling point is an unfortunate aspect of extractive distillation. Aniline is used instead.

7. Which factor does not decide a solvent?
a) Availability
b) Cost
c) Corrosivity
d) Viscosity

Answer: d [Reason:] Viscosity of solvent won’t decide which solvent to be chosen.

8. Solvent should not form ________
a) Hydrogen bond
b) London forces
c) Azeotrope
d) Mixture

Answer: c [Reason:] A solvent that forms a azeotrope is not used.

9. All the successful solvents are ________liquids.
a) Azeotrope forming
b) Hydrogen bonding
c) Reactive
d) Highly viscous

Answer: b [Reason:] All the successful solvents are hydrogen bonding liquids since a successful solvent should not form azeotrope.

10. It is ________ to find a solvent to separate same functional group.
a) Easy
b) Difficult
c) Impossible
d) Illogical

Answer: c [Reason:] It is impossible to find a solvent to separate same functional group.

## Set 4

1. Sequences based on heterogeneous azeotropic mixtures are :
a) Common
b) Rare
c) Expensive
d) Inexpensive

Answer: a [Reason:] Sequences based on heterogeneous azeotropic mixtures are common.

2. Heterogeneous azeotropic distillation is carried out by ___________ process.
a) Batch
b) Continuous
c) Batch and continuous
d) Feed

Answer: b [Reason:] Earlier the process was batch now it is continuous.

3. The reflux flow is 500 moles/hr and distillate flow is 100moles/hr, what is the value of ϕ by lever rule?
a) 5
b) 4
c) 2.5
d) 1.2

Answer: a [Reason:] ϕ= Reflux flow/ distillate flow=500/100=5.

4. The reflux flow is 400 moles/hr and distillate flow is 100moles/hr, what is the value of ϕ by lever rule?
a) 5
b) 4
c) 2.5
d) 1.2

Answer: b [Reason:] ϕ= Reflux flow/ distillate flow=400/100=4.

5. The reflux flow is 250 moles/hr and distillate flow is 100moles/hr, what is the value of ϕ by lever rule?
a) 5
b) 4
c) 2.5
d) 1.2

Answer: c [Reason:] ϕ= Reflux flow/ distillate flow=250/100=2.5.

6. The reflux flow is 240 moles/hr and distillate flow is 200moles/hr, what is the value of ϕ by lever rule?
a) 5
b) 4
c) 2.5
d) 1.2

Answer: a [Reason:] ϕ= Reflux flow/ distillate flow=240/200=2.5.

7. The reflux flow is 800 moles/hr and distillate flow is 500moles/hr, what is the value of ϕ by lever rule?
a) 50
b) 4
c) 2.5
d) 1.6

Answer: d [Reason:] ϕ= Reflux flow/ distillate flow=800/500=1.6.

8. The reflux flow is 5000 moles/hr and distillate flow is 250moles/hr, what is the value of ϕ by lever rule?
a) 5
b) 40
c) 20
d) 1.2

Answer: c [Reason:] ϕ= Reflux flow/ distillate flow=5000/2500=20.

9. If the value of ϕ is 20 by lever rule and reflux is 6000mol/hr what is distillate rate?
a) 300mol/hr
b) 30mol/hr
c) 400mol/hr
d) 40mol/hr

Answer: a [Reason:] ϕ= reflux flow/distillate flow ,hence distillate flow = reflux flow/ ϕ = 6000/200= 300.

10. If the value of ϕ is 20 by lever rule and reflux is 8000mol/hr what is distillate rate?
a) 300mol/hr
b) 30mol/hr
c) 400mol/hr
d) 40mol/hr

Answer: c [Reason:] ϕ= reflux flow/distillate flow ,hence distillate flow = reflux flow/ ϕ = 8000/200= 400.

11. If the value of ϕ is 10 by lever rule and reflux is 3500mol/hr what is distillate rate?
a) 350mol/hr
b) 30mol/hr
c) 450mol/hr
d) 40mol/hr

Answer: a [Reason:] ϕ= reflux flow/distillate flow ,hence distillate flow = reflux flow/ ϕ = 3500/10= 350.

12. If the value of ϕ is 20 by lever rule and reflux is 2000mol/hr what is distillate rate?
a) 100mol/hr
b) 30mol/hr
c) 400mol/hr
d) 40mol/hr

Answer: a [Reason:] ϕ= reflux flow/distillate flow ,hence distillate flow = reflux flow/ ϕ = 2000/20= 100.

13. If the value of ϕ is 25 by lever rule and reflux is 3000mol/hr what is distillate rate?
a) 12mol/hr
b) 120mol/hr
c) 240mol/hr
d) 40mol/hr

Answer: b [Reason:] ϕ= reflux flow/distillate flow ,hence distillate flow = reflux flow/ ϕ = 3000/25= 120.

## Set 5

1. Which manner is a chemical or biochemical plant not operated in?
a) Continuous
b) Batch-wise
c) Semi-continuous
d) Discontinuous

Answer: d [Reason:] If a chemical plant is operated in a discontinuous manner, time will be illogically wasted.

2. When is a separation process not required in a manufacturing process?
a) When there is a decomposition reaction
b) When there is a complete conversion
c) When the byproducts are in form of gases
d) When the reaction is reversible

Answer: b [Reason:] If there is a complete conversion of reactants to products, there will be no need for separation since no reactants are left.

3. If only 5% of Ethylene is converted to Ethylene glycol, why is there a need of separation process?
a) To feed more reactant to the reacting mixture
b) To remove the ethylene glycol formed
c) To recover the unreacted Ethylene Glycol
d) To start an intermediate reaction

Answer: c [Reason:] If the unreacted reactant is reused the cost of the manufacturing in turn shall be reduced since there will be less requirement for feeding new reactant and near complete conversion could be achieved.

4. Will the above reaction require a separation process?
a) Yes
b) No

Answer: b [Reason:] The above reaction will not require a separation process since there is a complete conversion of reactants to product.

5. How is the Diethyl Ether removed in the manufacturing of ethanol from ethylene?
a) Directly removed
b) Crude distillation column
c) Low pressure flash drum
d) Light-ends tower

Answer: d [Reason:] Diethyl ether is removed using a light ends tower easily.

6. Chemical reactions require feed mixtures from non-renewable resources like coal, petroleum. What is used in place of non-renewable sources?
a) Sunlight
b) Biomass
c) Biodiesel
d) Microorganisms

Answer: b [Reason:] Many of the products given by coal, petroleum are given by biomass too and it is less polluting.

7. Which of the following is a condition of operation for biochemical plant?
a) Metallic catalyst
b) Chemical catalyst
c) Elevated temperature
d) Non-pathologic state of the organism

Answer: d [Reason:] If any condition is used in a biochemical plant then there are chances of the organisms dying.So a nn-pathological state is preferred.

8. In a biochemical plant, what do the physiological conditions vary with?
a) The reaction
b) State of the products
c) The micro-organism
d) The ambient conditions

Answer: c [Reason:] The physiological condition has to be dependent on the micro-organism because micro-organism activity can be maximsed at certain conditions only.

9. How can be citric acid produced other than from lemons?
a) Aerobic fermentation of starch
b) Anaerobic fermentation of starch
c) Aerobic fermentation of glucose
d) Anaerobic fermentation of glucose

Answer: a [Reason:] The aerobic fermentation gives a considerate amount of citric acid required in various chemical and biochemical reactions.

10. Which of the following separation techniques is NOT used in the process of manufacturing of citric acid ?
a) Ultrafiltration
b) Ion-exchange
c) Crystallization
d) Distillation

Answer: d [Reason:] Distillation is not required in the manufacturing of itric acid since there are no two products forming which are needed to be separated having difference in boiling points.

11. What separation technique is used when a separation operation is accompanied by chemical reaction that facilitates separation?
a) Distillation
b) Fractional distillation
c) Reactive distillation
d) Fractional crystallization

Answer: c [Reason:] Reactive distillation is best employed in such conditions when the separation process is accompanied by chemical reaction like absorption of SO2 by limestone slurry.

12. Which of the following machines do not require a chemical separation technique?
a) The washing machine
b) Refrigerator
c) Coffee machine
d) Water cooler

Answer: c [Reason:] The coffee machine leaches oil from the coffee beans leaving behind the ingredients responsible for acidity and bitterness.

13. Which of the following is NOT an importance of separation process?
a) Reduces the operating cost
b) Reduces the risk of explosion
c) Reduces the probability of side reactions
d) Increases the speed of the reaction