Mass Transfer Mcqs for Chemical - Set 9

1)   In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________________ its relative saturation?

a. Lower than
b. Higher than
c. Equal to
d. Either A. or B., depends on the mixture composition
Answer  Explanation 

ANSWER: Lower than

Explanation:
No explanation is available for this question!


2)   At __________________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation?

a. Operating
b. Total
c. Minimum
d. Maximum permissible
Answer  Explanation 

ANSWER: Total

Explanation:
No explanation is available for this question!


3)   In physical terms, Schmidt number means _________________?

a. Thermal diffusivity/mass diffusivity
b. Thermal diffusivity/momentum diffusivity
c. Momentum diffusivity/mass diffusivity
d. Mass diffusivity/thermal diffusivity
Answer  Explanation 

ANSWER: Momentum diffusivity/mass diffusivity

Explanation:
No explanation is available for this question!


4)   Unit operation involved in the prilling of urea is_____________________?

a. Evaporation
b. Drying
c. Crystallisation
d. Both B. and C.
Answer  Explanation 

ANSWER: Both B. and C.

Explanation:
No explanation is available for this question!


5)   Degree of freedom for leaching and solvent extraction process is_____________________?

a. 0
b. 1
c. 2
d. 3
Answer  Explanation 

ANSWER: 3

Explanation:
No explanation is available for this question!


6)   With increase in temperature, the solubility of gases in liquids, at fixed pressure____________________?

a. Increases
b. Decreases
c. Remain same
d. Either A. or B., depends on the system
Answer  Explanation 

ANSWER: Decreases

Explanation:
No explanation is available for this question!


7)   The equipment used in the extraction of highly corrosive radioactive liquids is_______________________?

a. Pulse column
b. Spray column
c. Mixer settler
d. Baffle tower
Answer  Explanation 

ANSWER: Pulse column

Explanation:
No explanation is available for this question!


8)   Tea percolation employs___________________________?

a. Liquid-liquid extraction
b. Leaching
c. Absorption
d. None of these
Answer  Explanation 

ANSWER: Leaching

Explanation:
No explanation is available for this question!


9)   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  Explanation 

ANSWER: Large quantity of solvent is required to extract the solute

Explanation:
No explanation is available for this question!


10)   Bollman extractor___________________?

a. Is a static bed leaching equipment
b. Is used for extraction of oil from oilseed
c. Is a centrifugal extractor
d. Employs only counter-current extraction
Answer  Explanation 

ANSWER: Is used for extraction of oil from oilseed

Explanation:
No explanation is available for this question!


11)   In case of absorption, both the operating and equilibrium lines will be straight for______________?

a. Isothermal operation
b. Dilute solutions
c. Dilute solutions and isothermal operation
d. None of these
Answer  Explanation 

ANSWER: Dilute solutions and isothermal operation

Explanation:
No explanation is available for this question!


12)   The most economical range of absorption factor is____________________?

a. 0 to 0.5
b. 0 to 3
c. 1.25 to 2
d. 5 to 15
Answer  Explanation 

ANSWER: 1.25 to 2

Explanation:
No explanation is available for this question!


13)   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  Explanation 

ANSWER: Surface evaporation of unbound moisture occurs

Explanation:
No explanation is available for this question!


14)   Back-trapping in a distillation column ?

a. Increases tray efficiency
b. Decreases tray efficiency
c. Reduces pressure drop
d. Is desirable, as it provides improved vapour-liquid contact
Answer  Explanation 

ANSWER: Decreases tray efficiency

Explanation:
No explanation is available for this question!


15)   Rose oil is extracted from rose leaves using ____________ distillation?

a. High pressure
b. Low pressure
c. Extractive
d. Steam
Answer  Explanation 

ANSWER: Steam

Explanation:
No explanation is available for this question!


16)   The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases ‘A’ and ‘B’ is____________?

a. 1
b.
c. 0.5
d. 2
Answer  Explanation 

ANSWER: ∞

Explanation:
No explanation is available for this question!


17)   Which of the following is not a unit of mass transfer co-efficient ?

a. Moles transferred/ [(time) (area) (mole fraction)]
b. Moles transferred/ [(time) (area) (mass A/mass B)]
c. Moles transferred/ [(time) (area) (pressure)]
d. None of these
Answer  Explanation 

ANSWER: None of these

Explanation:
No explanation is available for this question!


18)   Dry bulb temperature of the gas is _____________ the wet bulb temperature?

a. Less than
b. More than
c. Equal to
d. None of these
Answer  Explanation 

ANSWER: More than

Explanation:
No explanation is available for this question!


19)   The equilibrium liquid composition compared to the vapor composition in case of________________?
Azeotropic mixture is


a. More
b. Less
c. Same
d. Either more or less; depends on the system
Answer  Explanation 

ANSWER: Same

Explanation:
No explanation is available for this question!


20)   Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled_________________?

a. And humidified
b. And dehumidified with increase in wet bulb temperature
c. At the same relative humidity
d. And dehumidified with decrease in wet bulb temperature
Answer  Explanation 

ANSWER: And dehumidified with decrease in wet bulb temperature

Explanation:
No explanation is available for this question!


21)   The value of Lewis number (Le = Sc/Pr) for air-water vapour system is around_________________?

a. 1
b. 0.24
c. 3.97
d. 600
Answer  Explanation 

ANSWER: 1

Explanation:
No explanation is available for this question!


22)   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 satur
d. All A , B. & C.
Answer  Explanation 

ANSWER: All A , B. & C.

Explanation:
No explanation is available for this question!


23)   The relation, Sc = Pr = 1, is valid, when the mechanism of ______________ transfer is same?

a. Heat and mass
b. Mass and momentum
c. Heat and momentum
d. Heat, momentum and mass
Answer  Explanation 

ANSWER: Heat and mass

Explanation:
No explanation is available for this question!


24)   McCabe-Thiele method________________?

a. Uses molal units for material and energy balance
b. Uses weight fractions to express liquid and vapour composition
c. Can use any type of units
d. Is more accurate than Ponchon-Savarit method
Answer  Explanation 

ANSWER: Uses molal units for material and energy balance

Explanation:
No explanation is available for this question!


25)   If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be _______________ percent?

a. 100
b. > 100
c. < 100
d. None of these
Answer  Explanation 

ANSWER: > 100

Explanation:
No explanation is available for this question!


26)   If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is________________?

a. 0.31
b. 0.107
c. 0.017
d. 0.215
Answer  Explanation 

ANSWER: 0.215

Explanation:
No explanation is available for this question!


27)   In case of ______________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated?

a. Molecular
b. Azeotropic
c. Extractive
d. Flash
Answer  Explanation 

ANSWER: Extractive

Explanation:
No explanation is available for this question!


28)   Moisture contained by a substance in excess of the equilibrium moisture is called the _______________ moisture?

a. Unbound
b. Free
c. Critical
d. Bound
Answer  Explanation 

ANSWER: Free

Explanation:
No explanation is available for this question!


29)   Hypersorption refers to a ________________ process?

a. Fixed bed absorption
b. Moving bed absorption
c. Fixed bed adsorption
d. Moving bed adsorption
Answer  Explanation 

ANSWER: Moving bed adsorption

Explanation:
No explanation is available for this question!


30)   In case of liquids, the binary diffusivity is proportional to (where, T = temperature) _____________________?

a. T
b. √T
c. T2
d. 1/T
Answer  Explanation 

ANSWER: T

Explanation:
No explanation is available for this question!


31)   The relative saturation of an unsaturated mixture of gas and vapor is independent of the___________________?

a. Nature of the vapor
b. Temperature of the mixture
c. Composition of the mixture
d. None of these
Answer  Explanation 

ANSWER: None of these

Explanation:
No explanation is available for this question!


32)   Advantage of continuous drying over batch drying is that the_____________________?

a. Drying cost per unit weight of dried product is less
b. Product with more uniform moisture content is produced
c. Equipment size required is smaller
d. All A , B. & C.
Answer  Explanation 

ANSWER: All A , B. & C.

Explanation:
No explanation is available for this question!


33)   An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is__________________?

a. 0.048
b. 0.079
c. 0.122
d. 0.152
Answer  Explanation 

ANSWER: 0.152

Explanation:
No explanation is available for this question!


34)   For an absorber, both equilibrium and operating line will be straight for _______________________?

a. Concentrated solution and non-isothermal operation
b. Dilute solution and non-isothermal operation
c. Dilute solution and isothermal operation
d. Concentrated solution and isothermal operation
Answer  Explanation 

ANSWER: Dilute solution and isothermal operation

Explanation:
No explanation is available for this question!


35)   Penetration model (theory) for mass transfer was enunciated by _____________________?

a. Danckwerts
b. Toor and Marcello
c. Higbie
d. Kissinevskii
Answer  Explanation 

ANSWER: Higbie

Explanation:
No explanation is available for this question!


36)   Milk is dried usually in a __________________ dryer?

a. Freeze
b. Spray
c. Tray
d. Rotary
Answer  Explanation 

ANSWER: Spray

Explanation:
No explanation is available for this question!


37)   Unit of molal diffusivity is____________________?

a. cm2/sec gm . mole
b. gm moles/cm2 . sec
c. gm moles/cm. sec
d. gm moles/cm2. sec
Answer  Explanation 

ANSWER: gm moles/cm. sec

Explanation:
No explanation is available for this question!


38)   In case of non-ideal gases and liquids, the molal diffusivity ________________?

a. Varies inversely as the pressure
b. Varies directly as the pressure
c. Is independent of pressure
d. Is equal to the volumetric diffusivity
Answer  Explanation 

ANSWER: Is independent of pressure

Explanation:
No explanation is available for this question!


39)   Which of the following is a suitable absorbent for removal of H2S from natural gas ?

a. Vetrocoke solution
b. Monoethanolamine (MEA)
c. Dilute
d. Hot water
Answer  Explanation 

ANSWER: Monoethanolamine (MEA)

Explanation:
No explanation is available for this question!


40)   Humid volume is the total volume in m3 of 1 kg of _____________________?

a. Vapour laden gas at 1 atm. and room temperature
b. Gas plus its accompanying vapour at 1 atm. and room temperature
c. Gas plus its accompanying vapour at 1 atm. and gas temperature
d. Vapour laden gas at 1 atm. and gas temperature
Answer  Explanation 

ANSWER: Gas plus its accompanying vapour at 1 atm. and gas temperature

Explanation:
No explanation is available for this question!