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## Interview MCQ Set 1

1. Low key and high key are _______ in volatility.
a) Same
c) Different
d) Not related

Answer: b [Reason:] Low key and high key are adjacent in volatility.

2. What is true if debutanizer is placed first in sequence?
a) N-butane is LK and isobutane is HK
b) Isobutane is LK and n-butane is HK
c) Both are LK
d) Both are HK

Answer: a [Reason:] If the debutanizer is first placed in sequence then the specifications require that N-butane is LK and isobutane is HK.

3. Where is the separation more difficult?
a) Debutanizer
b) Deisobutanizer
c) Both are simple
d) Both are difficult

Answer: b [Reason:] separation is more difficult in deisobutanizer.

4. The light key split is ______ whereas high key split is _______
a) Not sharp, sharp
b) Sharp, sharp
c) Sharp, not sharp
d) Not sharp, not sharp

Answer: c [Reason:] The lightkey split is sharp whereas high key split is not.

5. Why is column pressure fixed after design problems are solved?
a) Because the answer of design problems is column pressure
b) The design problems are independent of column pressure
c) The design problems are difficult
d) The design problems do not use column pressure while solving

Answer: c [Reason:] Since there are no available algorithms for solving design problems, the design problems are difficult. Hence column pressure is decided later.

6. If the :
Component distillate rate for LK (di) = 20
Component distillate rate for HK (dj) = 30
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] Only 1 stage is required here.

7. If the :
Component distillate rate for LK (di) = 20
Component distillate rate for HK (dj) = 30
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 3
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] Only 1 stage is required here.

8. If the :
Component distillate rate for LK (di) = 40
Component distillate rate for HK (dj) = 30
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 3
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] Only 1 stage is required here.

9. If the :
Component distillate rate for LK (di) = 50
Component distillate rate for HK (dj) = 40
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] Only 1 stage is required here.

10. If the :
Component distillate rate for LK (di) = 80
Component distillate rate for HK (dj) = 30
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: b [Reason:] Only 2 stages are required here.

11. If the :
Component distillate rate for LK (di) = 160
Component distillate rate for HK (dj) = 30
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: d [Reason:] Only 4 stages are required here.

12. If the :
Component distillate rate for LK (di) = 60
Component distillate rate for HK (dj) = 10
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: d [Reason:] Only 4 stages are required here.

13. If the :
Component distillate rate for LK (di) = 90
Component distillate rate for HK (dj) = 20
Bottom flow rate for LK (bi) = 30
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: d [Reason:] Only 4 stages are required here.

14. If the :
Component distillate rate for LK (di) = 50
Component distillate rate for HK (dj) = 10
Bottom flow rate for LK (bi) = 20
Bottom flow rate for HK (bj) = 10
Mean relative volatility is 2
What is the minimum number of stages required?
a) 1
b) 2
c) 3
d) 4

Answer: c [Reason:] Only 3 stages are required here.

## Interview MCQ Set 2

1. What happens in sublimation?
a) Solid vaporizes in liquid phase
b) A liquid vaporizes in gas phase
c) A gas solidifies
d) A solid vaporizes in gas phase without going in liquid phase

Answer: d [Reason:] In sublimation, a solid vaporizes in gas phase without going in liquid phase.

2. What happens in desublimation?
a) Solid vaporizes in liquid phase
b) A liquid vaporizes in gas phase
c) A gas solidifies without changing to liquid
d) A solid vaporizes in gas phase without going in liquid phase

Answer: c [Reason:] In desublimation, a gas solidifies in solid phase without going in liquid phase.

3. What are sublimation and desublimation governed by?
a) Liquid vapor pressure
b) Solid vapor pressure
c) Amount of solid present
d) Partial pressure of gas

Answer: b [Reason:] At low pressures both sublimation and desublimation are governed by solid vapor pressure.

4. What happens at equilibrium during sublimation?
a) Vapor pressure of liquid is equal to solid
b) Vapor pressure of solid is equal to vapor pressure of gas
c) Vapor pressure of solid is equal to partial pressure of solute in gas
d) Vapor pressure of solid is equal to partial pressure of solute in liquid

Answer: c [Reason:] During sublimation, the solid vapor pressure is equal to partial pressure of solute in gas.

5. When does the sublimation take place?
a) The partial pressure of solute in gas phase is more than solid vapor pressure
b) The partial pressure of solute I gas phase is more than solid vapor pressure
c) The vapor pressure is equal to partial pressure
d) When sufficient heat is applied

Answer: a [Reason:] Sublimation will only be taking place when the partial pressure is lesser in gas because the difference is the driving force.

6. What is the remainder product of sublimation called?
a) Subliment
b) Solute
c) Solvent
d) Sublimate

Answer: d [Reason:] The solid remaining is termed as sublimate.

7. Which of the following is not an example of sublimate?
a) Camphor
b) Naphthalene
c) Iodine
d) Nitrates

Answer: c [Reason:] Iodine is not a sublimate since it gets sublimated and not left behind.

8. Which of the following solids undergo sublimation?
a) Sodium chloride
b) Iodine crystals
c) Sodium carbonate
d) Sodium bicarbonate

Answer: b [Reason:] Iodine has high melting point and sublimes easily.

9. A mixture of ammonium chloride and sodium chloride is separated by using:
a) Distillation
b) Crystallization
c) Sublimation
d) Magnetic separation

Answer: c [Reason:] Ammonium chloride is sublimable, hence sublimation is used.

10. How is propylene-propane mixture separated?
a) Distillation
b) Crystallization
d) Sublimation

## Interview MCQ Set 3

1. What is humidification?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.

Answer: a [Reason:] For increasing the humidity of the air humidifier is used and the process is humidification.

2. What is dehumidification?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.

Answer: b [Reason:] Dehumidification has its use in air conditioning.

3. What is water-cooling?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.

Answer: d [Reason:] Water cooling is used to cool down the warm water before it can be resued.

4. What is gas cooling?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.

Answer: c [Reason:] For cooling hot air stream water can be used. However contents may change thereafter.

5. What is dry-bulb temperature?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a manner that sensible heat transferred from air to liquid is equal to latent heat required for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at same temperature.
d) Direct measure of moisture content in a gas

Answer: a [Reason:] It is the true temperature of air i.e not in contact with any vapor.

6. What is wet-bulb temperature?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a manner that sensible heat transferred from air to liquid is equal to latent heat required for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at same temperature.
d) Direct measure of moisture content in a gas

Answer: b [Reason:] The wet bulb temperature is measured by passing air over the bulb covered with wet cloth.

7. What is absolute humidity?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a manner that sensible heat transferred from air to liquid is equal to latent heat required for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at same temperature.
d) Direct measure of moisture content in a gas

Answer: d [Reason:] The mass of water vapor per unit mass of gas is called absolute humidity.

8. What is relative humidity?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a manner that sensible heat transferred from air to liquid is equal to latent heat required for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at same temperature.
d) Direct measure of moisture content in a gas

Answer: c [Reason:] The ratio of partial pressure of water vapor in air to the vapor pressure of water at same temperature is called relative humidity.

9. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.3
a) 6666.67
b) 10000
c) 5000
d) 4000

Answer: a [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 6666.67.

10. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.5
a) 6666.67
b) 10000
c) 5000
d) 4000

Answer: d [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients=4000.

11. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.2
a) 6666.67
b) 10000
c) 5000
d) 4000

Answer: b [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 10000.

12. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.4
a) 6666.67
b) 10000
c) 5000
d) 4000

Answer: c [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 5000.

13. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=100
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.2
a) 2000
b) 3000
c) 1000
d) 500

Answer: a [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 2000.

14. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 3
Ratio of heat and mass transfer coefficient is 0.1
a) 2000
b) 3000
c) 1000
d) 500

Answer: b [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 3000.

15. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=100
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.4
a) 2000
b) 3000
c) 1000
d) 500

Answer: d [Reason:] Depression in wet bulb temperature is = l*(Difference in saturated and humidity of ambient air)/Ratio of heat and mass transfer coefficients= 500.

## Interview MCQ Set 4

1. What is the type1 system for a solution?
a) The solute and solvent are immiscible in all proportions
b) The solute and solvent are miscible in all proportions
c) The concentration of solute is more than solvent
d) The concentration of solvent is more than solute

Answer: b [Reason:] For type1 system, the solute and solvent are miscible in all proportions.

2. What is the type2 system for a solution?
a) The solute and solvent are immiscible in all proportions
b) The solute and solvent are miscible in all proportions
c) The concentration of solute is more than solvent
d) The concentration of solvent is more than solute

Answer: a [Reason:] For type1 system, the solute and solvent are immiscible in all proportions.

3. How is phase equilibrium represented as told by hunter and nash?
a) Square
b) Oval
c) Equilateral triangle
d) Polygon

Answer: c [Reason:] According to hunter-nash method, an equilateral triangle is used to represent phase equilibrium.

4. What is the equilibrium curve in the liquid-liquid equilibrium data also called as?
a) Trinodal curve
b) Cynodal curve
c) Pinodal curve
d) Binodal curve

Answer: d [Reason:] It is called as bimodal curve since it has two nodes.

5. Solutropy is exhibited by which system?
a) Isopropanol-water-isopropyl alcohol
b) Water-benzene
c) Water-benzene-ethylalcohol
d) Isopropanol-water-benzene

Answer: d [Reason:] The phenomenon of solutropy is exhibited by the Isopropanol-water-benzene system.

6. What is the minimum solvent feed if feed is 200kg and the mass fraction of component A at feed is 0.7, at mixing is 0.5, and in the solvent is 0.4?
a) 400kg
b) 100kg
c) 200kg
d) 500kg

Answer: a [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 200*(0.7-0.5/0.5-0.4)=400kg.

7. What is the minimum solvent feed if feed is 200kg and the mass fraction of component A at feed is 0.7, at mixing is 0.6, and in the solvent is 0.4?
a) 400kg
b) 100kg
c) 200kg
d) 500kg

Answer: c [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 200*(0.6-0.5/0.5-0.4)=200kg.

8. What is the minimum solvent feed if feed is 250kg and the mass fraction of component A at feed is 0.8, at mixing is 0.5, and in the solvent is 0.4?
a) 3800kg
b) 650kg
c) 750kg
d) 500kg

Answer: c [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 250*(0.8-0.5/0.5-0.4)=750kg.

9. What is the minimum solvent feed if feed is 360kg and the mass fraction of component A at feed is 0.9, at mixing is 0.8, and in the solvent is 0.6?
a) 120kg
b) 720kg
c) 435kg
d) 180kg

Answer: d [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 360*(0.9-0.8/0.8-0.6)=180kg.

10. What is the minimum solvent feed if feed is 300kg and the mass fraction of component A at feed is 0.7, at mixing is 0.5, and in the solvent is 0.4?
a) 600kg
b) 100kg
c) 200kg
d) 500kg

Answer:a [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 300*(0.7-0.5/0.5-0.4)=600kg.

11. What is the minimum solvent feed if feed is 100kg and the mass fraction of component A at feed is 0.7, at mixing is 0.5, and in the solvent is 0.4?
a) 400kg
b) 100kg
c) 200kg
d) 500kg

Answer: c [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 100*(0.7-0.5/0.5-0.4)=200kg.

12. What is the minimum solvent feed if feed is 320kg and the mass fraction of component A at feed is 0.6, at mixing is 0.5, and in the solvent is 0.3?
a) 430kg
b) 160kg
c) 540kg
d) 500kg

Answer: b [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 320*(0.6-0.5/0.5-0.3)=160kg.

13. What is the minimum solvent feed if feed is 50kg and the mass fraction of component A at feed is 0.7, at mixing is 0.5, and in the solvent is 0.4?
a) 400kg
b) 100kg
c) 200kg
d) 500kg

Answer: b [Reason:] Since, Smin/F= (xa)F-(xA)M/(xa)M-(xA)S , then, Smin= 50*(0.7-0.5/0.5-0.4)=100kg.

## Interview MCQ Set 5

1. The ideal equations apply only till what pressure?
a) 305kPa
b) 315kPa
c) 325kPa
d) 345kPa

Answer: d [Reason:] The ideal equation can be applied only till 345kPa for components of similar molecular structure.

2. How is the molar volume calculated?
a) RT/V
b) RT/n
c) RT/P
d) RT/np

Answer: c [Reason:] Using ideal gas equation, the molar volume is calculated.

3. If the temperature of vapor is 400K and pressure is 20000 Pascal, what is the molar volume?
a) 0.15m3
b) 0.16 m3
c) 10 m3
d) 20 m3

Answer: b [Reason:] ϑv = RT/P.

4. Which equation is used to calculate liquid molar volume?
a) M/dL
b) M/P
c) M/RT
d) RT/P

Answer: a [Reason:] The equation M/dL is used.

5. Which equation is used for non-ideal solutions at ambient pressure?
a) K i = ϕ iL / ϕ iV
b) K i = γ iL ϕiL/ ϕ iV
c) K i = P i s /P
d) K iiL P i s /P

Answer: d [Reason:] Modified Roult’s law is used here.

6. The liquid enthalpy is calculated using:
a)

b)
c)
d)

Answer: d [Reason:] Equation is used.

7. How is the liquid mass density calculated?
a)
b)
c)
d)

Answer: a [Reason:] The formula is used.

8. If the temperature of vapor is 300K and pressure is 1atm , what is molar volume?
a) 0.04m3
b) 0.025 m3
c) 0.113 m3
d) 0.456 m3