Mass Transfer Set 15

Mechanical Engineering

Practice Mode Previous Next
On This Page

This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 15

Q1 | (NRe . NSc) is termed in mass transfer operation as the __________ number.
  • Stanton
  • Sherwood
  • Peclet
  • None of these
Answer: Peclet
Q2 | At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent
  • Increases
  • Decreases
  • Remains unchanged
  • Increases exponentially
Answer: Decreases
Q3 | With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux
  • Increases
  • Decreases
  • Remain same
  • May increase or decrease; depends on system
Answer: Decreases
Q4 | HETP is numerically equal to HTU, only when the operating line
  • Lies below the equilibrium line
  • Lies above the equilibrium line
  • And equilibrium lines are parallel
  • Is far from the equilibrium line
Answer: And equilibrium lines are parallel
Q5 | The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called
  • Decoction
  • Percolation
  • Elutriation or elution
  • None of these
Answer: Elutriation or elution
Q6 | __________ number indicates the ratio of the rates of the heat and mass transfer incase of acooling tower.
  • Sherwood
  • Stanton
  • Lewis
  • Peclet
Answer: Lewis
Q7 | The recovery of penicillin from the acidified fermentation broth is done by
  • Distillation
  • Evaporation
  • Absorption
  • Liquid extraction
Answer: Liquid extraction
Q8 | Drift in a cooling tower is
  • The water entrained by the circulating air
  • Dependent on the water lost by evaporation
  • Desirable
  • All (A), (B) & (C)
Answer: The water entrained by the circulating air
Q9 | In McCabe-Thiele method, at infinite reflux ratio
  • The overhead product is minimum
  • Both the operating lines coincide with diagonal
  • Both (A) and (B)
  • Neither (A) nor (B)
Answer: The overhead product is minimum
Q10 | Gaseous diffusivity at atmospheric pressure is of the order of __________ cm2/second.
  • 1
  • 1 to 5
  • 5 to 10
  • > 10
Answer: 1
Q11 | Absorption factor, for a fixed degree of absorption from a fixed amount of gas should be
  • 1
  • > 1
  • < 1
  • ? 1
Answer: > 1
Q12 | Pick out the wrong statement.
  • With decrease in feed temperature, the number of plates required for binary distillation decreases for a given ‘L/V’ ratio
  • The extraction per unit of total height for a short packed column is more effective than for a tall column, in case of liquid-liquid extraction
  • Natural draft cooling towers are made of ferroconcrete and its cross-section is wider at the bottom
  • Vander wall adsorption is also called chemisorption
Answer: Vander wall adsorption is also called chemisorption
Q13 | Molarity is defined as the number of gm moles of solute per __________ of solvent.
  • Litre
  • kg
  • gm
  • c.c
Answer: Litre
Q14 | If Rm is the minimum reflux ratio, the optimum reflux ratio may be around __________ Rm.
  • 1.2 to 1.5
  • 2.5 to 3
  • 3 to 4
  • 5
Answer: 1.2 to 1.5
Q15 | Adsorption is a unit operation which generally involves __________ systems.
  • Liquid-solid
  • Gas-solid
  • Fluid-solid
  • Solid-solid
Answer: Fluid-solid
Q16 | Surface renewal model of mass transfer was enunciated by
  • Toor and Marcello
  • Fick
  • Danckwerts
  • Stefan
Answer: Danckwerts
Q17 | Agitator is provided in a crystalliser for
  • Avoiding deposition on cooler surfaces
  • Formation of nuclei
  • Crystal growth
  • All (A), (B) and (C)
Answer: All (A), (B) and (C)
Q18 | Which of the following adsorbent is used to decolourise yellow glycerine?
  • Silica gel
  • Alumina
  • Fuller's earth
  • Activated carbon
Answer: Activated carbon
Q19 | Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of
  • Mass diffusivity to momentum diffusivity
  • Thermal diffusivity to mass diffusivity
  • Momentum diffusivity to thermal diffusivity
  • None of these
Answer: Thermal diffusivity to mass diffusivity
Q20 | Binary distillation involves the mass transfer by __________ at the gas-liquid interface.
  • Unidirectional diffusion from liquid to gas phase
  • Unidirectional diffusion from gas to liquid phase
  • Either 'a' or 'b'
  • A counter diffusion at an almost equal molar rate
Answer: A counter diffusion at an almost equal molar rate
Q21 | Corresponding to Nusselt number in heat transfer, the dimensionless group in masstransfer is the __________ number.
  • Sherwood
  • Schmidt
  • Peclet
  • Stanton
Answer: Sherwood
Q22 | Sand is dried in foundries in a _________drier.
  • Rotary
  • Fluidised bed
  • Vacuum
  • Spray
Answer: Fluidised bed
Q23 | Cox chart is useful in the design of
  • Distillation column
  • Evaporator
  • Dryer
  • Crystalliser
Answer: Distillation column
Q24 | Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are:
  • 4
  • 8
  • 9
  • 10
Answer: 9
Q25 | In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer.
  • The entire amount of C is transferred to solvent B
  • Less than 2 kg but more than 1 kg of C is transferred to solvent B
  • Less than 1 kg of C is transferred to B
  • No amount of C is tr
Answer: No amount of C is tr
Previous Next