591 + Mcqs in Mass Transfer Page 8 McqOptions

351.	_The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by$?
A.	Raising the temperature
B.	Lowering the total pressure
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

352.	_Positive deviation from Raoult's law means a mixture whose total pressure is$?
A.	Greater than that computed for ideality
B.	Less than that computed for ideality
C.	Less than the sum of the vapour pressure of the components
D.	None of these
Answer» B. Less than that computed for ideality

Discussion

353.	_Calcium ammonium nitrate (a fertiliser) is dried in a __________ dryer.$?
A.	Rotary
B.	Vacuum
C.	Tunnel
D.	Tray
Answer» B. Vacuum

Discussion

354.	_Which of the following is an undesirable property for an absorbing solvent?$?
A.	Low vapour pressure
B.	Low velocity
C.	Low freezing point
D.	None of these
Answer» E.

Discussion

355.	_Pick out the wrong statement:$?
A.	Absorption factor is constant, when the equilibrium and operating lines are straight
B.	In case of a stripper, the equilibrium curve is always below the operating line
C.	In case of an absorber, the operating line is always above the equilibrium curve
D.	In the absorption of low solubility gases, the liquid film is the controlling resistance
Answer» C. In case of an absorber, the operating line is always above the equilibrium curve

Discussion

356.	_Steam distillation is not recommended to be used, if the$?
A.	Azeotropic mixture is to be separated and the final product is miscible with water
B.	Liquids decompose, if distilled directly at atmospheric pressure
C.	Material can not be distilled by indirect heating even under low pressure, because of the high boiling temperature
D.	Material to be distilled is thermally unstable or has the tendency to react with other components associated with it, at the boiling temperature
Answer» B. Liquids decompose, if distilled directly at atmospheric pressure

Discussion

357.	_For gas absorption, low viscosity solvents are preferred, because of their$?
A.	Better flow characteristics
B.	Low pumping pressure drop
C.	Rapid absorption rates
D.	All of the above
Answer» E.

Discussion

358.	_Dried finished product sampled from various parts of a __________ dryer exhibits non-uniformity in the moisture content.$?
A.	Rotary
B.	Tray
C.	Freeze
D.	None of these
Answer» C. Freeze

Discussion

359.	_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

360.	_Raoult's law applies to the$?
A.	All liquid solutions
B.	Non-ideal solution only
C.	Non-volatile solute
D.	Solvents
Answer» E.

Discussion

361.	_The minimum number of theoretical plates is required for achieving a given separation in distillation column with$?
A.	No reflux
B.	Total reflux
C.	Zero reflux ratio
D.	Minimum reflux ratio
Answer» C. Zero reflux ratio

Discussion

362.	_Reboiler is considered as one theoretical plate, because$?
A.	Of the assumption that vapour and liquid leaving the reboiler are in equilibrium
B.	Vapour is recycled to the column
C.	Reboiler itself contains one plate
D.	None of these
Answer» B. Vapour is recycled to the column

Discussion

363.	_With the lowering of equiliDrium pressure, at a given temperature, the amount of ad-sorbate on the adsorbent$?
A.	Increases
B.	Decreases
C.	Remains same
D.	Either A or B, depends on the system
Answer» C. Remains same

Discussion

364.	_With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system)$?
A.	Increases
B.	Decreases
C.	Remains unaffected
D.	Increases Linearly
Answer» B. Decreases

Discussion

365.	_Penetration theory relates the average mass transfer co-efficient (K) with diffusivity (D) as$?
A.	K ‚Äö√ √π D
B.	K ‚Äö√ √π ‚Äö√ √∂D
C.	K ‚Äö√ √π D1.5
D.	K ‚Äö√ √π D2
Answer» C. K ‚Äö√ √π D1.5

Discussion

366.	_Ordinary diffusion process is also called __________ diffusion.$?
A.	Pressure
B.	Thermal
C.	Concentration
D.	Forced
Answer» D. Forced

Discussion

367.	_Which of the following plays an important role in problems of simultaneous heat and mass transfer?$?
A.	Lewis number
B.	Schmidt number
C.	Prandtl number
D.	Sherwood number
Answer» B. Schmidt number

Discussion

368.	_As the reflux ratio increases, the slope of the operating line for rectifying section$?
A.	Increases
B.	Decreases
C.	Remains constant
D.	Data insufficient, cannot be predicted
Answer» B. Decreases

Discussion

369.	_When the solvent dissolves very little of solute, then$?
A.	Solvent of low latent heat of vaporisation should be used
B.	Solvent of low freezing point should be used
C.	Large quantity of solvent is required to extract the solute
D.	Very small quantity of solvent is required
Answer» D. Very small quantity of solvent is required

Discussion

370.	_The Kundsen diffusivity is proportional to (where, T = absolute temperature)$?
A.	‚Äö√ √∂T
B.	T¬¨‚â§
C.	T
D.	T‚Äö√Ö¬•
Answer» B. T¬¨‚â§

Discussion

371.	_A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternery system containing twopairs of partially miscible liquids?$?
A.	0
B.	1
C.	2
D.	3
Answer» B. 1

Discussion

372.	_Steady state equimolal counter diffusion occurs in case of$?
A.	Leaching
B.	Absorption
C.	Binary phase distillation
D.	Liquid-liquid extraction
Answer» D. Liquid-liquid extraction

Discussion

373.	_The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same sytem is$?
A.	100
B.	10
C.	5
D.	1
Answer» C. 5

Discussion

374.	_In an absorption coloumn, the flooding velocity for random packing is __________ that for stacked/regular packing.$?
A.	Greater than
B.	Smaller than
C.	Equal to
D.	Either A, or B ; depends on the type of packing
Answer» C. Equal to

Discussion

375.	_In a moderately sized packed absorption tower, channeling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter$?
A.	> 4 :1
B.	< 8 : 1
C.	> 8:1
D.	< 6:1
Answer» D. < 6:1

Discussion

376.	_As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages$?
A.	Increase
B.	Decrease
C.	Remain unchanged
D.	Can either increase or decrease, depends on the system
Answer» C. Remain unchanged

Discussion

377.	_The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its$?
A.	Integral heat of adsorption
B.	Heat of wetting
C.	Differential heat of adsorption
D.	Heat of normal condensation
Answer» B. Heat of wetting

Discussion

378.	___________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower.$?
A.	Sherwood
B.	Stanton
C.	Lewis
D.	Peclet
Answer» D. Peclet

Discussion

379.	_In the constant rate period of the rate of drying curve for batch drying,$?
A.	Cracks develop on the surface of the solid
B.	Rate of drying decreases abruptly
C.	Surface evaporation of unbound moisture occurs
D.	None of these
Answer» D. None of these

Discussion

380.	_Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture.$?
A.	Bound
B.	Unbound
C.	Critical
D.	None of these
Answer» B. Unbound

Discussion

381.	_Degree of freedom for leaching and solvent extraction process is$?
A.	1
B.	3
C.	0
D.	2
Answer» C. 0

Discussion

382.	_Molarity is defined as the number of gm moles of solute per __________ of solvent.$?
A.	Litre
B.	Kg
C.	Gm
D.	C.c
Answer» B. Kg

Discussion

383.	_The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________$?
A.	1
B.	0.5
C.	10
D.	0
Answer» B. 0.5

Discussion

384.	_Absorption accompanied with chemical reaction is exemplified by the absorption of$?
A.	Ammonia in water
B.	Benzol present in coke oven gas by wash oil
C.	SO‚Äö√á√á in alkaline solution
D.	All of the above
Answer» D. All of the above

Discussion

385.	_Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as$?
A.	K ‚Äö√ √π D
B.	K ‚Äö√ √π ‚Äö√ √∂D
C.	K ‚Äö√ √π D1.5
D.	K ‚Äö√ √π D2
Answer» B. K ‚Äö√ √π ‚Äö√ √∂D

Discussion

386.	_Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapour-gas mixture is called the __________ temperature.$?
A.	Dry-bulb
B.	Wet-bulb
C.	Dew point
D.	Adiabatic saturation
Answer» C. Dew point

Discussion

387.	_It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).$?
A.	15 min
B.	51 min
C.	71 min
D.	94 min
Answer» D. 94 min

Discussion

388.	_During constant rate drying period, vaporisation rate per unit drying surface area$?
A.	Decreases with time
B.	Increases with time
C.	Does not change with time
D.	Does not affect the moisture content of the wet solid
Answer» D. Does not affect the moisture content of the wet solid

Discussion

389.	_With increase in temperature, the rate of leaching increases, because the$?
A.	Diffusivity of solute increases
B.	Viscosity of solvent decreases
C.	Thermal conductivity of solute increases
D.	None of these
Answer» B. Viscosity of solvent decreases

Discussion

390.	_The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an __________ law.$?
A.	Exponential
B.	Parabolic
C.	Linear
D.	Cubic
Answer» B. Parabolic

Discussion

391.	_Absorption factor method is used to calculate the number of ideal stages, when$?
A.	Operating line lies above the equilibrium line
B.	Operating line lies below the equilibrium line
C.	Both operating and equilibrium lines are parallel
D.	Pressure drop in the column is very high
Answer» D. Pressure drop in the column is very high

Discussion

392.	_The relative volatility of a binary mixture at the azeotropic composition is$?
A.	1
B.	> 1
C.	0
D.	‚Äö√ √ª
Answer» B. > 1

Discussion

393.	_In case of liquids, the binary diffusivity is proportional to (where, T = temperature)$?
A.	T
B.	‚Äö√ √∂T
C.	T¬¨‚â§
D.	1/T
Answer» B. ‚Äö√ √∂T

Discussion

394.	___________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction.$?
A.	Packed
B.	Bubble
C.	Spray
D.	Tray
Answer» C. Spray

Discussion

395.	_In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor.$?
A.	Increases with increase in
B.	Is one at unity value of
C.	Both A and B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

396.	_Extraction of pencillin employs a __________ extraction coloumn.$?
A.	Centrifugal
B.	Packed
C.	Plate
D.	None of these
Answer» B. Packed

Discussion

397.	_According to Poiseuille's law, the permeability for gas flow through a capillary is proportional to (where, ≈í¬∫ = gas viscosity)$?
A.	≈í¬∫
B.	1/≈í¬∫
C.	‚Äö√ √∂≈í¬∫
D.	≈í¬∫¬¨‚â§
Answer» C. ‚Äö√ √∂≈í¬∫

Discussion

398.	_The cooling effect in a cooling tower can not be increased by$?
A.	Increasing the air velocity over the wet surfaces
B.	Reducing the humidity of entering air
C.	Lowering the barometric pressure
D.	None of these
Answer» E.

Discussion

399.	_In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as$?
A.	Ri = Re/(1 - Re)
B.	Ri = (1 - Re)/Re
C.	Ri = Re
D.	Ri = Re/(1 + Re)
Answer» E.

Discussion

400.	_The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid )$?
A.	‚Äö√ √∂T
B.	T
C.	T1.5
D.	T3
Answer» C. T1.5

Discussion

Explore topic-wise MCQs in Chemical Engineering.

_The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by$?

_Positive deviation from Raoult's law means a mixture whose total pressure is$?

_Calcium ammonium nitrate (a fertiliser) is dried in a __________ dryer.$?

_Which of the following is an undesirable property for an absorbing solvent?$?

_Pick out the wrong statement:$?

_Steam distillation is not recommended to be used, if the$?

_For gas absorption, low viscosity solvents are preferred, because of their$?

_Dried finished product sampled from various parts of a __________ dryer exhibits non-uniformity in the moisture content.$?

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

_Raoult's law applies to the$?

_The minimum number of theoretical plates is required for achieving a given separation in distillation column with$?

_Reboiler is considered as one theoretical plate, because$?

_With the lowering of equiliDrium pressure, at a given temperature, the amount of ad-sorbate on the adsorbent$?

_With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system)$?

_Penetration theory relates the average mass transfer co-efficient (K) with diffusivity (D) as$?

_Ordinary diffusion process is also called __________ diffusion.$?

_Which of the following plays an important role in problems of simultaneous heat and mass transfer?$?

_As the reflux ratio increases, the slope of the operating line for rectifying section$?

_When the solvent dissolves very little of solute, then$?

_The Kundsen diffusivity is proportional to (where, T = absolute temperature)$?

_A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternery system containing twopairs of partially miscible liquids?$?

_Steady state equimolal counter diffusion occurs in case of$?

_The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same sytem is$?

_In an absorption coloumn, the flooding velocity for random packing is __________ that for stacked/regular packing.$?

_In a moderately sized packed absorption tower, channeling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter$?

_As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages$?

_The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its$?

___________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower.$?

_In the constant rate period of the rate of drying curve for batch drying,$?

_Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture.$?

_Degree of freedom for leaching and solvent extraction process is$?

_Molarity is defined as the number of gm moles of solute per __________ of solvent.$?

_The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________$?

_Absorption accompanied with chemical reaction is exemplified by the absorption of$?

_Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as$?

_Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapour-gas mixture is called the __________ temperature.$?

_It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).$?

_During constant rate drying period, vaporisation rate per unit drying surface area$?

_With increase in temperature, the rate of leaching increases, because the$?

_The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an __________ law.$?

_Absorption factor method is used to calculate the number of ideal stages, when$?

_The relative volatility of a binary mixture at the azeotropic composition is$?

_In case of liquids, the binary diffusivity is proportional to (where, T = temperature)$?

___________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction.$?

_In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor.$?

_Extraction of pencillin employs a __________ extraction coloumn.$?

_According to Poiseuille's law, the permeability for gas flow through a capillary is proportional to (where, ≈í¬∫ = gas viscosity)$?

_The cooling effect in a cooling tower can not be increased by$?

_In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as$?

_The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid )$?