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Interview MCQ Set 1

1. What does the solid-liquid separation operation don’t involve?
a) Gravity sedimentation
b) Magnetic separation
c) Filtration
d) Centrifugation

View Answer

Answer: b [Reason:] The solid-liquid separations always involve gravity sedimentation, filtration and centrifugation. Magnetic separation is not involved.

2. What process happens in leaching?
a) A solvent separates a mixture
b) Two solvents separate a mixture
c) A solvent selectively dissolves one of the component
d) The mixture is heated so that one solid sublimes and is separated.

View Answer

Answer: c [Reason:] Leaching is process where a solvent selectively dissolves some of the solid components from a multi component solid mixture.

3. What happens in an ideal leaching stage of a mixture of A and B?
a) The solvent dissolves Some B and some A
b) The solvent dissolves none of A and all B
c) The solvent dissolves all of A and B, which makes separation easier
d) The solvent does not dissolves any of A and B

View Answer

Answer: b [Reason:] In an ideal leaching stage the solvent dissolves none of A and all B which will make the separation most easy.

4. What increases the solute concentration?
a) Increasing viscosity of the liquid phases
b) Decreasing viscosity of liquid phases
c) Increasing temperature of liquid phases
d) Decreasing temperature of liquid phases

View Answer

Answer: a [Reason:] If the viscosity of the liquid phases is increased, the is an increase in the concentration of solute.

5. What is a eutectic point?
a) A temperature at which the mixture boils
b) The temperature at which the mixture gets out of equilibrium
c) The temperature at which the components have same molar flow rates
d) The temperature at which the mixture freezes

View Answer

Answer: d [Reason:] Eutectic point is a temperature at which a mixture freezes.

6. What is needed because of crystals occluding liquid?
a) Centrifugation
b) Distillation
c) Drying step
d) Decantation

View Answer

Answer: c [Reason:] A drying step is necessary because a crystal occludes solid

7. What is correct about the hydrate?
a) A high hydrate exists at low temperatures and low hydrste is unlikely to exist
b) A low hydrate exists at high temperature and a low hydrate exists at high temperature
c) A high hydrate exists at high temperature and a low hydrate exists at high temperature.
d) A hydrate does not exist at high temperature

View Answer

Answer: b [Reason:] Due to more water molecules present , the high hydrate will be unstable at high temperatures.

8. What happens during adsorption process of solid-liquid separation?
a) The adsorbent adsorbs liquid in the interior and solid in the exterior
b) The adsorbent adsorbs liquid In the interior and the exterior
c) The adsorbent adsorbs solid in the interior and liquid in the exterior
d) The adsorbent adsorbs solid in the interior and the exterior

View Answer

Answer: b [Reason:] In adsorption, a solid agent adsorbs liquid phasein the interior and the exterior.

9. Which laboratory methods give a rough prediction about adsorption-equilibrium curves?
a) Isobaric calculation
b) Flow charts
c) Adsorption isotherms
d) Absorption isotherms

View Answer

Answer: c [Reason:] Adsorption isotherms provide a rough idea about the adsorption-equilibrium.

10. The freundlich equation is of the form:
a) qi = Aci (1/n)
b) cBQ=q*BS
c) qi = Aci(n)
d) qi = Aci

View Answer

Answer: a [Reason:] The freundlich isotherm is of the form qi = Aci (1/n) which can be converted to y=mx + c by taking logarithms on both sides.

Interview MCQ Set 2

1. Which of the following is Fourier law of heat conduction?
a) q z = k*dT z/dZ
b) q z = – k*dT z /dZ
c) q z = k*T z /dZ
d) q z = k*dQ z /dZ

View Answer

Answer: b [Reason:] Fourier’s law of heat conduction states that the heat is directly proportional to change is temperature gradient.

2. Which of the following is correct representation of Fick’s law of diffusion?
a) J z = -D*dc a /dz
b) J z = -D*dT/ds
c) J z = D*dc a /dz
d) J z = -D*c a /dz

View Answer

Answer: a [Reason:] The molar flux is directly proportional to the concentration gradient.

3. What id D ab called in the Fick’s law?
a) Thermal conductivity
b) Density coefficient
c) Diffusivity
d) Electrical conductivity

View Answer

Answer: c [Reason:] The constant D ab is called as mutual diffusion coefficient or diffusivity.

4. Which of the following formulae is right about molar flux?
a) N a = x A N – D ab (dx a /d z )
b) N a = x A N – (dx a /d z )
c) N a = x A N – cD ab
d) N a = x A N – cD ab (dx a /d z )

View Answer

Answer: d [Reason:] The correct formula for molar flux of a component is N a = x A N – cD ab (dx a /d z ).

5. Which of the following is untrue about equimolar diffusion?
a) N a + N b =0
b) J a = J b
c) N=0
d) N a = -cD BA (dx b /dz)

View Answer

Answer: b [Reason:] J a = J b durig equimolar diffusion.

6. Which of the following is FALSE about unimolar diffusion?
a) N b = N a
b) N= N a
c) N a = x a N a – cD ab (dx a /dz)
d) X b N a = cD ba (dx b /dz)

View Answer

Answer: a [Reason:] For unimolar diffusion, N b =0.

7. Why does the diffusion of A with respect to B occur?
a) Due to concentration gradient
b) To to volume gradient
c) Due to velocity gradiet
d) Due to change in heat

View Answer

Answer: a [Reason:] Concentration gradient is responsible for diffusion.

8. Which diffusion occurs when turbulent motion is there?
a) Molar diffusion
b) Eddy diffusion
c) Charge diffusion
d) No diffusion

View Answer

Answer: b [Reason:] Due to turbulence there is a cause of eddy diffusion.

9. When is fick’s law applied?
a) For passive diffusion down the concentration gradient
b) Passive osmosis along concentration gradient
c) Active osmosis along concentration gradient
d) Active and passive movement of molecule along concentration gradient

View Answer

Answer: a [Reason:] Fick’s law is used when there is passive diffusion down the concentration gradient.

10. Which of the following is TRUE?
a) Mass transfer in ordinary mixture occurs due to temperature gradient
b) Mass transfer is proportional to the area the molecules travel
c) Net transfer stops when concentrations are equal
d) The mass transfer is proportional to the area normal to the direction of mass transfer.

View Answer

Answer: d [Reason:] The mass transfer is proportional to the area normal to the direction of mass transfer. The areal along the transfer is not considered.

Interview MCQ Set 3

1. When it is not assumed that the vapor and liquid leaving a stage are not at same temperature?
a) When pressure changes from stage to stage
b) When temperature changes from stage to stage
c) When concentration of solute changes from stage to stage
d) When concentration of vapor changes from stage to stage

View Answer

Answer: b [Reason:] When temperature changes from stage to stage it cannot be assumed that the vapor and liquid leaving a stage are not at same temperature.

2. To determine the actual number of required plates for a trayed column, what must be used?
a) K values
b) Process efficiency
c) Stage efficiency
d) Equilibrium between vapor and liquid

View Answer

Answer: c [Reason:] To determine the actual number of required plates for a trayed column, stage effieiency or tray efficiency must be used.

3. What is the formula for overall stage efficiency given by lewis?
a) E o = Nt /N a
b) Eo = Nt N a
c) Eo = Nt -N a
d) Eo = Nt +N a

View Answer

Answer: a [Reason:] The formula for overall stage efficiency given by Lewis is E o = Nt /N a , where Eo is the fractional stage efficiency, N t is the calculated equilibrium stages and N a is the actual number of required plates.

4. The overall stage efficiency is not a complex function of which of the following?
a) Geometry and design of contacting trays
b) Flow rates and flow paths for liquid and vapor phases
c) Compositions and properties of vapor and liquid phases
d) Material of the tray used

View Answer

Answer: d [Reason:] The overall stage efficiency is not dependent on the material of the plates used.

5. What is the height added above the top tray to remove the entrained liquid?
a) 2ft
b) 4ft
c) 6ft
d) 8ft

View Answer

Answer: b [Reason:] 4ft is added above the top tray to remove the entrained liquid.

6. What is the height added below the bottom tray for bottom surge capacity?
a) 4ft
b) 6ft
c) 8ft
d) 10ft

View Answer

Answer: d [Reason:] The height of 10ft is added below the bottom tray for bottom surge capacity.

7. When are the columns in series preferred?
a) If the estimated height is above 100ft
b) If the estimated height Is above 150ft
c) If the estimated height is above 250ft
d) If the number of trays are less

View Answer

Answer: c [Reason:] If the estimated height is above 250ft, columns in series are preferred.

8. What is the tallest column in the world?
a) 240ft
b) 248ft
c) 300ft
d) 338ft

View Answer

Answer: d [Reason:] The tallest column in the world located at Shell Company, texas is 338ft.

9. What are the actual numbers of required plates when the overall stage efficiency is 0.8 and the calculated equilibrium stages are 4?
a) 2
b) 3
c) 5
d) 7

View Answer

Answer: c [Reason:] By E o = Nt /N a , N a = 4/0.8=5.

10. What are the actual numbers of required plates when the overall stage efficiency is 0.9 and the calculated equilibrium stages are 9?
a) 12
b) 11
c) 5
d) 10

View Answer

Answer: d [Reason:] By E o = Nt /N a , N a = 9/0.9=10.

11. What are the actual numbers of required plates when the overall stage efficiency is 0.7 and the calculated equilibrium stages are 2.8?
a) 2
b) 4
c) 5
d) 7

View Answer

Answer: b [Reason:] By E o = Nt /N a , N a = 2.8/0.7=4.

12. What are the actual numbers of required plates when the overall stage efficiency is 0.6 and the calculated equilibrium stages are 4.8?
a) 8
b) 3
c) 5
d) 7

View Answer

Answer: a [Reason:] By E o = Nt /N a , N a= 4.8/0.6=8.

13. What is the overall stage efficiency if the calculated equilibrium stages are 8 and the actual plates required are 12?
a) 0.75
b) 0.6
c) 0.56
d) 0.12

View Answer

Answer: a [Reason:] By E o = Nt /N a , E o = 8/12 = 0.75.

14. What is the overall stage efficiency if the calculated equilibrium stages are 9 and the actual plates required are 11?
a) 0.75
b) 0.82
c) 0.56
d) 0.12

View Answer

Answer: b [Reason:] By E o = Nt /N a , E o = 9/1 = 0.82.

15. What is the overall stage efficiency if the calculated equilibrium stages are 7 and the actual plates required are 13?
a) 0.75
b) 0.6
c) 0.54
d) 0.12

View Answer

Answer: c [Reason:] By E o = Nt /N a , E o = 7/13 = 0.54.

Interview MCQ Set 4

1. Calculate concentration of solvent if
Concentration of impurity is Wo=1%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 4.5*10-4
c) 16.6*10-3
d) 4.15*10-3

View Answer

Answer: a [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 8.3*10-3.

2. Calculate concentration of solvent if
Concentration of impurity is Wo=2%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 4.5*10-4
c) 16.6*10-3
d) 4.15*10-3

View Answer

Answer: c [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 16.6*10-3.

3. Calculate concentration of solvent if
Concentration of impurity is Wo=0.5%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 4.5*10-4
c) 16.6*10-3
d) 4.15*10-3

View Answer

Answer: d [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 4.15*10-3.

4. Calculate concentration of solvent if
Concentration of impurity is Wo=0.6%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.5*10-3
b) 4.9*10-3
c) 32.6*10-3
d) 23*10-3

View Answer

Answer: b [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 4.9*10-3.

5. Calculate concentration of solvent if
Concentration of impurity is Wo=0.7%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 7.8*10-4
c) 78*10-3
d) 5.8*10-3

View Answer

Answer: d [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 5.8*10-3.

6. Calculate concentration of solvent if
Concentration of impurity is Wo=3%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 32.89*10-4
c) 16.6*10-3
d) 24.9*10-3

View Answer

Answer: d [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 24.9*10-3.

7. Calculate concentration of solvent if
Concentration of impurity is Wo=0.8%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 79*10-4
c) 6.64*10-3
d) 7.9*10-3

View Answer

Answer: c [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 6.64*10-3.

8. Calculate concentration of solvent if
Concentration of impurity is Wo=0.9%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 9.8*10-4
c) 7.47*10-3
d) 8*10-3

View Answer

Answer: c [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 7.47*10-3.

9. Calculate concentration of solvent if
Concentration of impurity is Wo=0.4%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 3.32*10-4
c) 6.63*10-3
d) 4.15*10-3

View Answer

Answer: b [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 3.32*10-3.

10. Calculate concentration of solvent if
Concentration of impurity is Wo=1.5%
Solid liquid equilibrium distribution coefficient is K=0.7
z/l= 0.8
a) 8.3*10-3
b) 4.5*10-4
c) 12.45*10-3
d) 9*10-3

View Answer

Answer: c [Reason:] Since Ws= Wo(1-(1-K)exp(-K*z/l)), hence Ws= 12.45*10-3.

Interview MCQ Set 5

1. What do the pressure filtration devices consist that remains suspended while allowing the fluid in which the solids are suspended to pass through?
a) Semipermeable membrane
b) Mesh barrier
c) No barrier
d) Column

View Answer

Answer: b [Reason:] The pressure filtration devices consist of Mesh barrier that remains suspended while allowing the fluid in which the solids are suspended to pass through.

2. The filtration models are based on which laws?
a) Pascals law
b) Roult’s law
c) Avogadro’s law
d) Darcy’s law

View Answer

Answer: d [Reason:] The filtration models are based on darcy’s law deve;oped in 1855 to describe flow of water in sand beds.

3. Which of the following is the correct representation of the darcy’s law?
a) (-k/µ)(dp/dz)
b) (-kµ)(dp/dz)
c) (k/µ)(dp/dz)
d) (kµ)(dp/dz)

View Answer

Answer: a [Reason:] The correct representation of the darcy’s law is (-k/µ)(dp/dz) since it is inversely proportional to the viscosity of the medium.

4. Why a pump that delivers slurry to a filtration unit at constant pressure not a positive displacement pump?
a) Because it operates at variable floe rate
b) Because it operates at constant flow rates
c) Because the time of flow is different
d) Because the time of flow is same

View Answer

Answer: b [Reason:] A pump that delivers slurry to a filtration unit at constant pressure not a positive displacement pump because it operates at constant flow rates.

5. If the reported filter area A= 1m2
Viscosity µ = 5*10-4
Pressure difference = 100
And the intercept is 500
What is the value of medium’s resistance to flow?
a) 1*108
b) 5*108
c) 6*108
d) 2.5*108

View Answer

Answer: a [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=1*108.

6. If the reported filter area A= 1m2
Viscosity µ = 1*10-4
Pressure difference = 100
And the intercept is 500
What is the value of medium’s resistance to flow?
a) 1*108
b) 5*108
c) 6*108
d) 2.5*108

View Answer

Answer: b [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=5*108.

7. If the reported filter area A= 1m2
Viscosity µ = 5*10-4
Pressure difference = 100
And the intercept is 3000
What is the value of medium’s resistance to flow?
a) 1*108
b) 5*108
c) 6*108
d) 2.5*108

View Answer

Answer: c [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=6*108.

8. If the reported filter area A= 1m2
Viscosity µ = 2*10-4
Pressure difference = 100
And the intercept is 500
What is the value of medium’s resistance to flow?
a) 1*108
b) 5*108
c) 6*108
d) 2.5*108

View Answer

Answer: d [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=2.5*108.

9. If the reported filter area A= 1m2
Viscosity µ = 10*10-4
Pressure difference = 100
And the intercept is 500
What is the value of medium’s resistance to flow?
a) 0.5*108
b) 23*108
c) 11*108
d) 5.3*108

View Answer

Answer: a [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=0.5*108.

10. If the reported filter area A= 1m2
Viscosity µ = 5*10-4
Pressure difference = 100
And the intercept is 700
What is the value of medium’s resistance to flow?
a) 12*108
b) 5.5*108
c) 9.5*108
d) 1.4*108

View Answer

Answer: d [Reason:] Since Rm= ΔPA(intercept)/µ, hence Rm=1.4*108.