Mass Transfer Set 7

Mechanical Engineering

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This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 7

Q1 | The apex of an equilateral-triangular coordinate (in ternary liquid system) represents a/an
  • Pure component
  • Binary mixture
  • Ternary mixture
  • Insoluble binary system
Answer: Pure component
Q2 | __________ extractor is used for the concentration of radioactive nuclear waste.
  • Pulsed column
  • Sieve plate
  • Mixer-settler
  • Bollman
Answer: Pulsed column
Q3 | Removal of __________ exemplifies an adsorption unit operation.
  • Uranium from its ore
  • Water from petrol
  • Ammonia from coke oven gas
  • Mustard oil from mustard seed
Answer: Water from petrol
Q4 | Use of packed towers for distillation is generally limited to the
  • Small sizes
  • Multi-component distillation
  • High pressure operation
  • Vacuum distillation
Answer: Small sizes
Q5 | Dimension of mass diffusivity is the same as that of
  • Kinematic viscosity
  • Dynamic viscosity
  • Surface tension
  • Pressure
Answer: Kinematic viscosity
Q6 | Paper industry employs __________ driers.
  • Cylinder
  • Rotary
  • Spray
  • Fluidised bed
Answer: Cylinder
Q7 | Pick out the wrong statement
  • A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity
  • When water is cooled from 80 to 70°C by exposure to the air with a wet bulb temperature of 60°C, then both the approach & the range would be 10°C
  • For unsaturated air-water vapor mixture at atmospheric conditions, the wet bulb temperature & adiabatic cooling lines are the same
  • Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure
Answer: Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure
Q8 | Laboratory determination of the diffusivity of vapor is done by __________ method.
  • Wetted wall column
  • Gilliland's
  • Winkelmann's
  • Wike's
Answer: Winkelmann's
Q9 | The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force.)
  • Kc = Kp = Km
  • Kc = Kp/RT = Km . RT/P
  • Kc = Kp . RT = Km . RT/p
  • None of these
Answer: Kc = Kp . RT = Km . RT/p
Q10 | Pick out the wrong statement:
  • Change in barometric pressure does not affect the relative humidity
  • In case of a packed tower, the operating velocity is about half of the flooding velocity, generally
  • 'Elution' means the desorption of the adsorbed solute by a solvent
  • The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity
Answer: The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity
Q11 | The temperature of water cooled in cooling tower is always __________ temperature of entering air.
  • More than the wet bulb
  • Less than the wet bulb
  • Equal to the wet bulb
  • Equal to the dry bulb
Answer: More than the wet bulb
Q12 | Reverse osmosis is also called
  • Dialysis
  • Electrodialysis
  • Diffusion
  • Ultra-filtration
Answer: Ultra-filtration
Q13 | Design calculation for multiple component distillation is done by
  • Ponchon-Savarit method
  • McCabe-Thiele method
  • Enthalpy concentration method
  • Tray to tray calculations
Answer: Tray to tray calculations
Q14 | Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in
  • Decreased solute solubility
  • Large minimum liquid to gas (L/G) ratio
  • Large number of trays
  • All (A), (B) and (C)
Answer: All (A), (B) and (C)
Q15 | The unit of volumetric diffusivity is
  • cm2/sec
  • cm/sec
  • cm3/sec
  • cm2/sec2
Answer: cm2/sec
Q16 | Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant
  • Humidity
  • Velocity
  • Temperature
  • All (A), (B) & (C)
Answer: All (A), (B) & (C)
Q17 | The diffusivity (D) in a binary gas mixture is related to the pressure (P) as
  • D ? P 0.5
  • D ? 1/P 0.5
  • D ? 1/P
  • D ? 1/P 1.5
Answer: D ? 1/P
Q18 | In liquid extraction, if the selectivity is unity, then
  • Separation of the constituents is the most effective
  • No separation will occur
  • Amount of solvent required will be minimum
  • Solvent flow rate should be very low
Answer: No separation will occur
Q19 | Can the efficiency of a plate in the distillation tower be greater than 100%?
  • Yes
  • Normally not; but is possible if infinite number of plates are put
  • Never
  • Yes; if the reflux ratio is maximum
Answer: Never
Q20 | H2S present in naphtha reformed gas is removed by absorbing with
  • Ethanolamine
  • K2CO3
  • HCl
  • Vacuum gas oil
Answer: Ethanolamine
Q21 | Dorr thickener is an equipment used for
  • Classification
  • Sedimentation
  • Clarification
  • Leaching
Answer: Sedimentation
Q22 | With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent
  • Increases
  • Decreases
  • Remain same
  • Either (A) or (B), depends on the system
Answer: Decreases
Q23 | Mass transfer co-efficient is directly proportional to DAB according to the __________ theory.
  • Film
  • Penetration
  • Surface-renewal
  • None of these
Answer: Film
Q24 | A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is:
  • 0.54
  • 1.04
  • 1.24
  • 1.94
Answer: 1.24
Q25 | __________ extractor uses centrifugal force for separating the two phases.
  • Treybal
  • Scheibel
  • Podbielniak
  • None of these
Answer: Podbielniak
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