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Multiple choice question for engineering

Set 1

1. An azeotrope occurs, when there is same _______
a) Bubble Point
b) Boiling Point
c) VLE Composition
d) Pressure Equilibrium

View Answer

Answer: c [Reason:] An azeotrope occurs when the composition of a vapor in equilibrium with a liquid mixture has the same composition as the liquid.

2. A minimum-boiling azeotrope can be formed by?
a) Azeotrope entrainer
b) Any chemical
c) Water
d) Benzene

View Answer

Answer: a [Reason:] A minimum-boiling azeotrope can be formed by an azeotrope-forming entrainer to an existing azeotropic mixture or close-boiling mixture for which separation by conventional distillation is not feasible.

3. An example of Minimum azeotrope is?
a) Benzene and Water
b) Ethanol and Water
c) Water and Ethyl Alcohol
d) Benzene and Alcohol

View Answer

Answer: b [Reason:] Ethanol and water form a minimum-boiling azeotrope with ethanol as the major component and therefore ethanol cannot be completely dehydrated by conventional distillation.

4. Homogeneous azeotropes exist when the vapor is in equilibrium with?
a) Single liquid phase
b) Single Solid phase
c) Dual Phase
d) Triple Phase

View Answer

Answer: a [Reason:] Homogeneous azeotropes exist when the vapor is in equilibrium with a single liquid phase. In a homogeneous system, entrainer must be recovered by extraction.

5. Heterogeneous azeotropes exist when the vapor is in equilibrium with?
a) Dual liquid phase
b) Dual Solid phase
c) Dual Phase
d) Triple Phase

View Answer

Answer: c [Reason:] Heterogeneous azeotropes exist when the vapor is in equilibrium with two liquid phases. Heterogeneous azeotropic distillation is widely used for the separation of azeotropes.

6. Esters are produced by reacting alcohols with?
a) Organic acids
b) Pure base
c) P-Xylene
d) PTA

View Answer

Answer: a [Reason:] Esters are produced by reacting alcohols with organic acids. The reaction is reversible and therefore unless one of the products is removed.

7. Young performed his azeotropic dehydration of alcohol by?
a) Continuous Method
b) Batch Method
c) Stage Method
d) Full Method

View Answer

Answer: b [Reason:] Young, who demonstrated the first industrial application, azeotropic distillation is still used today in the production and dehydration of alcohol.

8. Ethanol is dehydrogenated oxidatively to acetaldehyde using a _____ Catalyst.
a) Ag
b) Pt
c) Pb
d) Hg

View Answer

Answer: a [Reason:] In acetaldehyde oxidation, ethanol is dehydrogenated oxidatively to acetaldehyde using a silver, brass or bronze catalyst.

9. A relative volatility close to unity could indicate the presence of?
a) Separation Point
b) Pinch Point
c) Deep Point
d) Extraction Point

View Answer

Answer: b [Reason:] A relative volatility close to unity could indicate the presence of a pinch point. It is technically feasible to separate components that form a pinch point.

10. The esterification of alcohols involves?
a) Elimination reaction
b) Substitution reaction
c) Irreversible reaction
d) Reversible reaction

View Answer

Answer: d [Reason:] The esterification of alcohols involves a reversible reaction. Being equilibrium limited, the reaction will not go to completion in the presence of the product.

Set 2

1. The azeotrope in the ethanol–water binary system has a composition of ____ ethanol.
a) 89%
b) 59%
c) 88%
d) 99%

View Answer

Answer: a [Reason:] The azeotrope in the ethanol–water binary system has a composition of 89 mole per cent of ethanol, starting with a mixture containing a lower proportion of ethanol.

2. PSD is called?
a) Pressure Straight Desorption
b) Pressure Swing Distillation
c) Pressure Singer Desorption
d) Parameter Swing Distillation

View Answer

Answer: b [Reason:] The pressure swing distillation (PSD) uses the azeotropic composition on the system pressure to break the azeotrope.

3. For easy separation, the relative volatility αi,j tends to?
a) 0
b) 1
c) 1.5
d) 0.5

View Answer

Answer: b [Reason:] The separation at the azeotropic point is not possible, because of the reason that the relative volatility αi,j is equal to one.

4. If the boiling temperature isobar exhibits, an extremal point then mixture is said to be
a) Fully azeotropic
b) Totally azeotropic
c) Tangentially azeotropic
d) Partially azeotropic

View Answer

Answer: c [Reason:] If the boiling temperature isobar exhibits an extremal point located at the pure component edges, i.e., at zero concentration for one or several of the components in the mixture.

5. At constant pressure, there exhibits a nearly extreme point at zero concentration for one or several of the components this point is called?
a) Tangent pitch
b) Elliptical pitch
c) Parabolic pitch
d) Circular pitch

View Answer

Answer: a [Reason:] This phenomenon is also called a tangent pinch, such mixtures are of great practical importance, examples of common tangentially zeotropic mixtures are acetone and water.

6. Positive deviation from Raoult’s law results in?
a) Minimum boiling azeotrope
b) Maximum boiling azeotrope
c) Tangential azeotrope
d) Elliptical azeotrope

View Answer

Answer: a [Reason:] The attraction between identical molecules (A-A and B-B) is stronger than between different molecules (A-B), This may cause the formation of a minimum-boiling azeotrope and heterogeneity.

7. Negative deviation from Raoult’s law results in?
a) Minimum boiling azeotrope
b) Maximum boiling azeotrope
c) Tangential azeotrope
d) Elliptical azeotrope

View Answer

Answer: b [Reason:] The attraction between different molecules (A-B) is the strongest, This may cause the formation of a maximum-boiling azeotrope.

8. Ideal mixture obeys Raoult’s law results in?
a) Minimum boiling azeotrope
b) Maximum boiling azeotrope
c) Tangential azeotrope
d) Ideal azeotropes

View Answer

Answer: d [Reason:] The components have similar physiochemical properties, the intermolecular forces between identical and different molecules (A-A, B-B and A-B) are equal.

9. The most commonly used membrane technology for liquid azeotropic mixtures is?
a) Pervaporation
b) Evaporation
c) De-evaporation
d) Condensation

View Answer

Answer: a [Reason:] The most commonly used membrane technology for liquid azeotropic mixtures is pervaporation with low pressure on the permeate side of the membrane so as to evaporate the permeate.

10. When the entrainer reacts preferentially and reversibly with one of the original mixture components then it is called?
a) Non-Reactive distillation
b) Reactive distillation
c) Extractive distillation
d) Prime distillation

View Answer

Answer: b [Reason:] The reaction product is distilled out from the non-reacting component and the reaction is reversed to recover the initial component, the distillation and reaction is usually carried out in one column.

Set 3

1. The temperature where the first vapor is formed, when heating a liquid consisting of two or more components
a) Dew point
b) Bubble point
c) Final point
d) Aniline point

View Answer

Answer: a [Reason:] The temperature where the first vapor is formed when heating a liquid consisting of two or more components Bubble point, while when the first drop of aniline separates out is called the aniline point. Nc∑Yi ∑Kixi.

2. The below equation holds for
distillation-design-questions-answers-bubble-point-method-q2
a) K and X relation
b) K and Bubble relation
c) Components and K values relation
d) Nc Relation

View Answer

Answer: b [Reason:] At the bubble point, the following relationship holds always, representing Nc as number of components and yi as the mole fraction of all components.

3. The K in the below equation holds for
distillation-design-questions-answers-bubble-point-method-q3
a) Distribution Factor
b) Henry Factor
c) Vapor Factor
d) Dew factor

View Answer

Answer: a [Reason:] K is the distribution coefficient, defined as the ratio of mole fraction in the vapor phase, these are not always equal but are somehow equivalent to each other.

4. When Raoult’s law and Dalton’s law hold for the mixture, the K factor is
a) Pi/P
b) Yi/Xi
c) Y*/X
d) X*/X

View Answer

Answer: a [Reason:] When Raoult’s law and Dalton’s law hold for the mixture, the K factor is Pi/P, indicating Pi as the partial pressure of system and P as total pressure.

5. The bubble point method is the most widely used for
a) Pore size determination
b) Bubble size determination
c) Stages determination
d) Tray determination

View Answer

Answer: a [Reason:] The bubble point method is the most widely used for Pore size determination, Underwood, Gilliland, McCabe are used for stages and tray determination.

6. The BP Method generally work best for
a) Narrow Boiling systems
b) Ideal systems
c) Nearly ideal systems
d) Any systems

View Answer

Answer: c [Reason:] The BP Method generally work for Narrow Boiling systems, Ideal systems and nearly ideal systems as boiling point of a component does not vary much as compared to other properties.

7. To perform a Bubble Point Test, gas is applied to
a) All the filter
b) Both side of wetted filter
c) One side of a wetted filter
d) Not specified

View Answer

Answer: c [Reason:] To perform a Bubble Point Test, gas is applied to one side of a wetted filter, with the tubing downstream.

8. The equation below gives us the
distillation-design-questions-answers-bubble-point-method-q8
a) Reflux equation
b) Dew point equation
c) Stage efficiency equation
d) Capillary Rise equation

View Answer

Answer: d [Reason:] The equation above gives us the Capillary Rise equation, d is the diameter of the capillary and P is the pressure applied and cos is the angle of inclination.

9. Bubble point equation is used for
a) Reflux and feed rate
b) Vapor and liquid composition
c) Venting and filtration
d) Equilibrium phases

View Answer

Answer: c [Reason:] Bubble point equation is used for Venting and filtration purposes as the liquid evaporates the filtration of pure liquid can be achieved using condensation technique.

10. θ (theta) stands for
a) Convergence promoter
b) Catalyst promoter
c) Dynamic value
d) Bubble Extract point

View Answer

Answer: a [Reason:] θ (theta) stands for Convergence promoter, TBp is defined as the bubble extract point and lambda as the catalyst parameter.

Set 4

1. The depressed region of the tray is called?
a) Seal pan
b) Crack pot
c) Jack port
d) Trap port

View Answer

Answer: a [Reason:] An alternative is a depressed down comer seal which region of the tray is called as seal pan.

2. The area of the tray column that contain the bubble cap is called as?
a) Biasing area
b) Active tray area
c) Down comer area
d) Perforated area

View Answer

Answer: b [Reason:] In a reverse flow that liquid entering the tray flows over an area this tray area is defined as the active area.

3. The blank region on the tray deck is called as?
a) Cracking gin
b) Sleeping zone
c) Calming zone
d) Professor zone

View Answer

Answer: c [Reason:] Disengagement of liquid occurs before the liquid overflows this region is called as the calming zone.

4. For a better design a manhole, these should be located at every
a) 10-15 trays
b) 20-25 trays
c) 45-50 trays
d) 50-60 trays

View Answer

Answer: a [Reason:] Manholes are provided for each 10-15 trays for access of a workman into the column for inspection.

5. Misdistribution of feeds are also called as?
a) Vapor channeling
b) Liquid channeling
c) Solid channeling
d) Back tracking

View Answer

Answer: a [Reason:] Vapor channeling is reduces the tray efficiency and increases turbulence, thus reducing the efficiency of the system.

6. Leakage of small fractions of feed from one tray to another is called as?
a) Dumping
b) Clicking
c) Greasing
d) Weeping

View Answer

Answer: d [Reason:] Liquid flows from a tray to the lower one through perforations openings of tray, weeping causes reduction of tray efficiency.

7. The carryover of suspended vapor droplets, into upper tray is defined
a) Entrainment
b) Tray efficiency
c) Dumping
d) Mega Weeping

View Answer

Answer: a [Reason:] The chances of entrainment are more if the gas velocity is high as it bubbles the column this is called entrainment.

8. The excessive accumulation of the liquid on the tray causes phenomena called?
a) Regime
b) Flooding
c) Spray regime
d) Down comer

View Answer

Answer: b [Reason:] Abnormal liquid depth increase the pressure this causes liquid hold up which is called as flooding.

9. The mathematical value of down comer backup is?
a) hc + ht+ had
b) hc – ht+ had
c) hc – ht – had
d) hc + ht

View Answer

Answer: a [Reason:] Here hc + ht+ had = hdb where hc = liquid height, ht = height of tray, had = down comer apron.

10. The forth height (hf), is given
a) hdbd
b) hdbd
c) ht
d) ht

View Answer

Answer: a [Reason:] Here hf = hdbd where θd = is the average relative forth density and hdb = down comer backup.

Set 5

1. Bubble cap is a perforated tray with, additional
a) Trays
b) Camps
c) Pooches
d) Holes

View Answer

Answer: a [Reason:] Bubble cap are provided with trays and valve trays are the most popular type of trays assembled.

2. Sieve tray after installation gives, a Vapor
a) Bypass effect
b) Valve effect
c) Multiorifice effect
d) Manhole effect

View Answer

Answer: c [Reason:] The sieve tray gives a multi orifice effect to stop the process called weeping and liquid hold up.

3. An example of zero down comers is?
a) Dual tray
b) Sieve tray
c) Cap tray
d) Bubble tray

View Answer

Answer: a [Reason:] A dual flow tray is a sieve tray with no down comers. This tray operates with liquid continuously.

4. Continuous flow of liquid causes?
a) Greater efficiency
b) Lesser efficiency
c) Affordable cost
d) Extra cost

View Answer

Answer: b [Reason:] When the liquid flow continuously weeping through holes then the efficiency gets lesser and greater the problems.

5. In the packed column, the fluid flows from
a) Top to bottom
b) Bottom to top
c) Left to right
d) Right to left

View Answer

Answer: a [Reason:] In pure column based equipment the fluid flows from top to bottom, gas flows from bottom and liquid from the top.

6. Stages are also called?
a) Trays
b) Cascades
c) Flow regime
d) Initial plate

View Answer

Answer: c [Reason:] The stages are also called as cascade, upper and tower are also called cascade, Disturbance’s in the flow is called as flow regimes.

7. The tray holds up a dispersion of?
a) Solid-liquid
b) Gas -gas
c) Gas-liquid
d) Liquid-liquid

View Answer

Answer: c [Reason:] It allows the gas to flow through the holes or passages the gas bubbles vigorously and form a gas-liquid dispersion.

8. The open region provides between the tray floor and cap bottom is called as?
a) Pocket clearance
b) Skirt clearance
c) Tray clearance
d) Carp clearance

View Answer

Answer: b [Reason:] The ball shaped cap rests on the three short legs and placed at 1200 this is called as skirt clearance.

9. The sieve tray is also called as?
a) Perforated tray
b) Non porous tray
c) Porous tray
d) Clear tray

View Answer

Answer: a [Reason:] As the small holes are made by punching holes into the tray these are called perforations and thus the tray is called perforated tray.

10. If the tower hole area is 366 m2 and the tower cross section is 10 m2, the free area fraction is?
a) 785 m2
b) 366.56 m2
c) 36.6 m2
d) 3660 m2

View Answer

Answer: c [Reason:] As free area = (hole area/tower CSA) = 366/10 = 36.6 m2.