8247 + Mcqs in Chemical Engineering Page 46 McqOptions

2251.	Decoction refers to the use of solvent
A.	at ambient temperature
B.	at its boiling point
C.	in its vapor form
D.	none of these
Answer» C. in its vapor form

Discussion

2252.	Flash distillation is suitable for separating the constituents of a binary system, which
A.	form minimum boiling azeotrope.
B.	have very wide boiling points.
C.	have very close boiling points.
D.	form constant boiling azeotrope.
Answer» C. have very close boiling points.

Discussion

2253.	The rough value of diffusion co-efficient of water vapor into air at 25 C may be about __________ cm2/sec.
A.	0.25
B.	2.5
C.	1.25
D.	0.0025
Answer» B. 2.5

Discussion

2254.	Extraction of coffee from its seed is done by
A.	liquid-liquid extraction.
B.	leaching.
C.	extractive distillation.
D.	steam distillation.
Answer» C. extractive distillation.

Discussion

2255.	In azeotropic mixture, the equilibrium vapour composition is
A.	more than liquid composition.
B.	less than liquid composition.
C.	same as liquid composition.
D.	independent of pressure.
Answer» D. independent of pressure.

Discussion

2256.	With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux
A.	increases
B.	decreases
C.	remains same
D.	may increase or decrease ; depends on system.
Answer» C. remains same

Discussion

2257.	The ratio of Murphree plate efficiency to point efficiency is 1 in a __________ flow model.
A.	plug
B.	perfectly mixed
C.	both (a) & (b)
D.	neither (a) nor (b)
Answer» C. both (a) & (b)

Discussion

2258.	Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of
A.	mass diffusivity to momentum diffusivity.
B.	thermal diffusivity to mass diffusivity.
C.	momentum diffusivity to thermal diffusivity.
D.	none of these.
Answer» C. momentum diffusivity to thermal diffusivity.

Discussion

2259.	Molecular seives are porous
A.	alumina.
B.	silica.
C.	synthetic zeolites crystals/metal alumino-silicates.
D.	none of these.
Answer» D. none of these.

Discussion

2260.	The ratio of Murphree plate efficiency to point efficiency is always > 1 in a __________ flow model.
A.	plug
B.	perfectly mixed
C.	both (a) & (b)
D.	neither (a) nor (b)
Answer» B. perfectly mixed

Discussion

2261.	Tea percolation employs
A.	liquid-liquid extraction
B.	leaching
C.	absorption
D.	none of these
Answer» C. absorption

Discussion

2262.	Calcium ammonium nitrate (a fertiliser) is dried in a __________ dryer.
A.	rotary
B.	vacuum
C.	tunnel
D.	tray
Answer» B. vacuum

Discussion

2263.	A binary mixture of benzene and cyclohexane is separated by
A.	flash vaporisation
B.	extractive distillation
C.	solvent extraction
D.	ordinary distillation
Answer» C. solvent extraction

Discussion

2264.	Cox chart is useful in the design of
A.	distillation column
B.	evaporator
C.	dryer
D.	crystalliser
Answer» B. evaporator

Discussion

2265.	Dew point of an air-water vapor mixture
A.	decreases with decrease in pressure.
B.	at constant humidity & total pressure is fixed.
C.	corresponding to any point on the humidity chart is obtained by projecting a line through this point parallel to the temperature axis and to the saturation curve.
D.	all 'a', 'b' & 'c'.
Answer» E.

Discussion

2266.	In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.
A.	interface
B.	gas phase
C.	liquid phase
D.	all 'a', 'b' & 'c'
Answer» B. gas phase

Discussion

2267.	Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations.
A.	Sherwood number in mass transfer is analogous to Nusselt number in heat transfer.
B.	Prandtl number in heat transfer is analogous to Schmidt number in mass transfer.
C.	Reynolds number in mass transfer is analogous to Grashoff number in heat transfer.
D.	Reynolds number remains the same in both heat and mass transfer.
Answer» D. Reynolds number remains the same in both heat and mass transfer.

Discussion

2268.	The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is
A.	0
B.
C.	-ve
D.	+ve
Answer» D. +ve

Discussion

2269.	The individual mass transfer co-efficients (moles/m2 . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?
A.	liquid side
B.	gas side
C.	interfacial
D.	both liquid and gas side
Answer» C. interfacial

Discussion

2270.	In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of __________ mm.
A.	3-5
B.	5-11
C.	8-15
D.	12-18
Answer» C. 8-15

Discussion

2271.	The stress developed in a material without any permanent set is called the
A.	ultimate stress
B.	yield stress
C.	elastic limit
D.	breaking stress
Answer» D. breaking stress

Discussion

2272.	In a shell and tube heat exchanger, the 'tube pitch' is defined as the
A.	O.D. of the tube for square pitch.
B.	shortest distance between two adj acent tube holes.
C.	shortest centre to centre distance between adjacent tubes.
D.	none of these.
Answer» D. none of these.

Discussion

2273.	Overall distillation column efficiency for most of the refinery columns can be given by (for = 0.07 - 1.4 cp and relative volatility < 4) (where = overall column efficiency, % = molal average viscosity of feed at average column temperature and pressure, cp p = pressure drop per tray, psi)
A.	= 17 - 61.1 log
B.	<img src="/_files/images/chemical-engineering/process-equipment-and-plant-design/565-83-1.png">
C.	= 1.66 - 0.25 log
D.	= 0.25 log - 1.67
Answer» B. <img src="/_files/images/chemical-engineering/process-equipment-and-plant-design/565-83-1.png">

Discussion

2274.	The value of fouling factor depends upon the
A.	characteristic of process fluid.
B.	velocity of process fluid containing suspended solids.
C.	suspended solids in the fluid.
D.	all (a), (b) and (c).
Answer» E.

Discussion

2275.	In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.
A.	10
B.	20
C.	30
D.	35
Answer» B. 20

Discussion

2276.	Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size & number of tubes and operated at the same liquid flow rate.
A.	2
B.	1/2
C.	4
D.	8
Answer» E.

Discussion

2277.	Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe-Thiele's method ?
A.	Sensible heat changes for vapour & liquid are negligibly small.
B.	Reflux is not a saturated liquid.
C.	Molar latent heat of the two components are equal.
D.	Heat of mixing of normal liquid is assumed to be zero.
Answer» C. Molar latent heat of the two components are equal.

Discussion

2278.	In a heat exchanger, shell side fluid velocity can be changed by changing the tube
A.	layout
B.	pitch
C.	both (a) & (b)
D.	neither (a) nor (b)
Answer» D. neither (a) nor (b)

Discussion

2279.	Steam distillation is used for separation of high boiling
A.	substances from non-volatile impurities.
B.	volatile impurity from still higher boiling substances.
C.	both (a) and (b).
D.	neither (a) nor (b).
Answer» D. neither (a) nor (b).

Discussion

2280.	The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will
A.	increase
B.	decrease
C.	remains same
D.	depend on saturated boiling point; may increase or decrease
Answer» B. decrease

Discussion

2281.	Rose oil is extracted from rose leaves using __________ distillation.
A.	high pressure
B.	low pressure
C.	extractive
D.	steam
Answer» E.

Discussion

2282.	Hypersorption refers to a __________ process.
A.	fixed bed absorption
B.	moving bed absorption
C.	fixed bed adsorption
D.	moving bed adsorption
Answer» E.

Discussion

2283.	Which of the following is the correct ternery diagram for liquid-liquid extraction system comprising of two pairs partly soluble (e.g., chlorobenzene-water-methyl ethyl ketone system) ?
A.	<img src="/_files/images/chemical-engineering/mass-transfer/317-500-1.png">
B.	<img src="/_files/images/chemical-engineering/mass-transfer/317-500-2.png">
C.	<img src="/_files/images/chemical-engineering/mass-transfer/317-500-3.png">
D.	None of these.
Answer» B. <img src="/_files/images/chemical-engineering/mass-transfer/317-500-2.png">

Discussion

2284.	When both the fluids flow concurrently in an absorber, the slope of the operating line is
A.	- ve
B.	+ ve
C.	1
D.	-1
Answer» B. + ve

Discussion

2285.	Which of the following same diameter columns gives lowest pressure drop per unit height ?
A.	Bubble-cap column
B.	Sieve-plate column
C.	Packed column (stacked)
D.	Randomly packed column
Answer» D. Randomly packed column

Discussion

2286.	Diffusion in concentrated solutins differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution.
A.	degree of ideality
B.	viscosity
C.	both 'a '& 'b'
D.	neither 'a' nor 'b'
Answer» D. neither 'a' nor 'b'

Discussion

2287.	Stage efficiency in a leaching process depends on the
A.	time of contact between the solid and the solution
B.	rate of diffusion of the solute through the solid and into the liquid
C.	both (a) and (b)
D.	vapour pressure of the solution
Answer» D. vapour pressure of the solution

Discussion

2288.	Operating velocity in a packed tower is usually __________ the flooding velocity.
A.	half
B.	twice
C.	equal to
D.	more than
Answer» B. twice

Discussion

2289.	Which of these columns incurs the lowest pressure drop ?
A.	Packed column (with stacked packing)
B.	Packed column (with dumped packing)
C.	Bubble plate column
D.	Pulse column
Answer» B. Packed column (with dumped packing)

Discussion

2290.	In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase.
A.	gas
B.	liquid
C.	both (a) & (b)
D.	neither (a) nor (b)
Answer» C. both (a) & (b)

Discussion

2291.	Which of the following remains constant during evaporative cooling process with recirculated water supply ?
A.	Relative humidity
B.	Partial pressure of vapour
C.	Wet bulb temperature
D.	None of these
Answer» D. None of these

Discussion

2292.	For stripping of a gas in a counter current stripper, the operating line
A.	lies above the equilibrium curve.
B.	lies below the equilibrium curve.
C.	can lie above or below the equilibrium curve.
D.	is always parallel to the equilibrium curve.
Answer» D. is always parallel to the equilibrium curve.

Discussion

2293.	Hydrogenation of oil is carried out in a/an __________ in Vanaspati manufacturing plant.
A.	agitated vessel
B.	sieve tray column
C.	bubble cap column
D.	packed tower
Answer» B. sieve tray column

Discussion

2294.	Sides of equilateral-triangular co-ordinates (on which ternary liquid system is plotted) represent
A.	a pure component.
B.	a binary mixture.
C.	a ternary mixture.
D.	partially miscible ternary system.
Answer» C. a ternary mixture.

Discussion

2295.	In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when
A.	saturated feed is not used.
B.	an azeotrope forms.
C.	the latent heat of vaporisation of the more and less volatile components are greatly different.
D.	a total condenser is used.
Answer» E.

Discussion

2296.	In an interphase mass transfer process, the lesser the solubility of a given solute in a liquid, the higher are the chances that the transfer process will be
A.	liquid phase resistance-controlled.
B.	gas phase resistance controlled.
C.	impossible.
D.	driven by a non-linear driving force.
Answer» C. impossible.

Discussion

2297.	As the reflux ratio decreases, the
A.	separation becomes more efficient.
B.	number of plates increases.
C.	column diameter increases.
D.	none of these.
Answer» C. column diameter increases.

Discussion

2298.	A packed tower compared to a plate tower for a particular mass transfer operation
A.	incurs smaller pressure drop.
B.	allows installation of cooling coils.
C.	is less costly when built in large sizes/diameters.
D.	is more suitable, if suspended solids are present in fluid streams.
Answer» B. allows installation of cooling coils.

Discussion

2299.	Which of the following is the most commonly used leaching solvent in vegetable oil industry ?
A.	Phenol
B.	Hexane
C.	Furfurol
D.	Liquid SO
E.	<sub>2</sub>
Answer» C. Furfurol

Discussion

2300.	In an absorber, HETP does not vary with the
A.	flow rate of liquid
B.	flow rate of gas
C.	type and size of packing
D.	none of these
Answer» E.

Discussion

Explore topic-wise MCQs in Engineering.

Decoction refers to the use of solvent

Flash distillation is suitable for separating the constituents of a binary system, which

The rough value of diffusion co-efficient of water vapor into air at 25 C may be about __________ cm2/sec.

Extraction of coffee from its seed is done by

In azeotropic mixture, the equilibrium vapour composition is

With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux

The ratio of Murphree plate efficiency to point efficiency is 1 in a __________ flow model.

Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of

Molecular seives are porous

The ratio of Murphree plate efficiency to point efficiency is always &gt; 1 in a __________ flow model.

Tea percolation employs

Calcium ammonium nitrate (a fertiliser) is dried in a __________ dryer.

A binary mixture of benzene and cyclohexane is separated by

Cox chart is useful in the design of

Dew point of an air-water vapor mixture

In case of absorption &amp; stripping, the interface of the liquid &amp; gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.

Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations.

The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is

The individual mass transfer co-efficients (moles/m2 . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?

In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of __________ mm.

The stress developed in a material without any permanent set is called the

In a shell and tube heat exchanger, the 'tube pitch' is defined as the

Overall distillation column efficiency for most of the refinery columns can be given by (for = 0.07 - 1.4 cp and relative volatility &lt; 4) (where = overall column efficiency, % = molal average viscosity of feed at average column temperature and pressure, cp p = pressure drop per tray, psi)

The value of fouling factor depends upon the

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size &amp; number of tubes and operated at the same liquid flow rate.

Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe-Thiele's method ?

In a heat exchanger, shell side fluid velocity can be changed by changing the tube

Steam distillation is used for separation of high boiling

The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will

Rose oil is extracted from rose leaves using __________ distillation.

Hypersorption refers to a __________ process.

Which of the following is the correct ternery diagram for liquid-liquid extraction system comprising of two pairs partly soluble (e.g., chlorobenzene-water-methyl ethyl ketone system) ?

When both the fluids flow concurrently in an absorber, the slope of the operating line is

Which of the following same diameter columns gives lowest pressure drop per unit height ?

Diffusion in concentrated solutins differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution.

Stage efficiency in a leaching process depends on the

Operating velocity in a packed tower is usually __________ the flooding velocity.

Which of these columns incurs the lowest pressure drop ?

In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase.

Which of the following remains constant during evaporative cooling process with recirculated water supply ?

For stripping of a gas in a counter current stripper, the operating line

Hydrogenation of oil is carried out in a/an __________ in Vanaspati manufacturing plant.

Sides of equilateral-triangular co-ordinates (on which ternary liquid system is plotted) represent

In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when

In an interphase mass transfer process, the lesser the solubility of a given solute in a liquid, the higher are the chances that the transfer process will be

As the reflux ratio decreases, the

A packed tower compared to a plate tower for a particular mass transfer operation

Which of the following is the most commonly used leaching solvent in vegetable oil industry ?

In an absorber, HETP does not vary with the

The ratio of Murphree plate efficiency to point efficiency is always > 1 in a __________ flow model.

In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.

Overall distillation column efficiency for most of the refinery columns can be given by (for = 0.07 - 1.4 cp and relative volatility < 4) (where = overall column efficiency, % = molal average viscosity of feed at average column temperature and pressure, cp p = pressure drop per tray, psi)

Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size & number of tubes and operated at the same liquid flow rate.