chemical engineering Mcqs
1951. The diffusivity D. in a binary gas mixture is related to the pressure (P) as__________________?
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A. D ? 1/P0.5

B. D ? 1/P1.5

C. D ? P0.5

D. D ? 1/P
1952. The process employing desorption of the absorbed solute by a solvent is called____________________?
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A. Osmosis

B. Elution

C. Reverse osmosis

D. Sublimation

1953. Diameter to height ratio for a raschig ring is_____________________?
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A. 8

B. 1

C. 0.5

D. 2

1954. Sand is dried in foundries in a ______________________drier?
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A. Rotary

B. Vacuum

C. Spray

D. Fluidised bed
1955. The main reason for dividing a tall packed tower into series of small towers is to________________________?
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A. Reduce liquid hold up

B. Minimise the overall pressure drop

C. Avoid flooding

D. Avoid channelling
1956. Dimension of mass diffusivity is the same as that of_____________________?
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A. Pressure

B. Surface tension

C. Kinematic viscosity

D. Dynamic viscosity

1957. At what percentage (by volume) of alcohol composition, it forms an azeotrope with water ?
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A. 90

B. 91.5

C. 95

D. 99

1958. _______________ diffusion is used for separating the isotopes of methane ?
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A. Thermal

B. Force

C. Concentration

D. Pressure

1959. In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________________ its relative saturation?
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A. Higher than

B. Equal to

C. Lower than

D. Either A. or B., depends on the mixture composition

1960. Minimum reflux ratio in a distillation column results in__________________?
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A. Optimum number of trays

B. Minimum number of trays

C. Maximum condenser size

D. Minimum reboiler size

1961. With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent______________________?
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A. Increases

B. Remain same

C. Decreases

D. Either A. or B., depends on the system

1962. At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes______________________?
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A. ?

B. None of these

C. 0

D. 1

1963. Bound moisture is that liquid which exerts an equilibrium vapor pressure ________________ that of the pure liquid at the given temperature ?
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A. More than

B. Less than

C. Equal to

D. Either A. or B.; depends on the solid

1964. Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant____________________?
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A. Temperature

B. Velocity

C. All A., B. & C.

D. Humidity

1965. Which of the following operations does not involve leaching ?
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A. Removing nicotine from its water solution by kerosene

B. Dissolving pharmaceutical products from bark or roots

C. Dissolving sugar from the cells of the beet

D. Dissolving gold from ores

1966. Freundlich equation applies to the adsorption of solute from_____________________?
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A. Dilute solutions, over a small concentration range

B. Gaseous solutions at high pressure

C. Concentrated solutions

D. None of these

1967. During constant rate period, the rate of drying decreases with the______________________?
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A. Decrease in air temperature

B. Increase in air humidity

C. Both A. and B.

D. Neither A. nor B.

1968. Use of natural draft cooling tower is practised, when the air has low ?
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A. Humidity

B. Temperature

C. Both A. & B.

D. Neither A. nor B.

1969. Pick out the wrong statement pertaining to the analogy between equations of heat and mass_________________?
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A. nsfer operations.

B. Sherwood number in mass transfer is analogous to Nusselt number in heat transfer

C. Prandtl number in heat transfer is analogous to Schmidt number in mass transfer

D. Reynolds number in mass transfer is analogous to Grashoff number in heat transfer

E. Reynolds number remains the same in both heat and mass transfer

1970. The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is__________________?
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A. #NAME?

B. -ve

C. ?

D. 0

1971. Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the____________________?
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A. None of these

B. Packing may be crushed due to thermal expansion/contraction of the components of the

C. Pressure drop in the equipment will be very high

D. ipments</strong>

E. Viscosity variation of the fluids may cause channelling/flooding

1972. Rayleighs equation applies to _________________ distillation?
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A. Flash

B. Continuous

C. Differential

D. Steam

1973. With increase in temperature, the rate of leaching increases, because the___________________?
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A. Diffusivity of solute increases

B. Thermal conductivity of solute increases

C. None of these

D. Viscosity of solvent decreases

1974. Very tall packed towers are divided into series of beds to___________________?
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A. Avoid channelling

B. Reduce liquid hold-up

C. Avoid flooding

D. Reduce the overall pressure drop

1975. The slope of 9-line is determined by the______________________?
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A. Reflux ratio

B. Thermal condition of the feed

C. Plate efficiency to be achieved

D. Relative volatility

1976. The McCabe ?L law states that the____________________?
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A. Linear crystal growth rate depends on the crystal size

B. Linear crystal growth rate does not depend on the crystal size

C. Linear crystal growth rate depends on the degree of super-saturation

D. Molar heats of vaporisation of components are nearly equal

1977. Steam distillation is used for separation of high boiling ____________________?
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A. Substances from non-volatile impurities

B. Volatile impurity from still higher boiling substances

C. Both A. and B.

D. Neither A. nor B.

1978. Penetration model (theory) for mass transfer was enunciated by _____________________?
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A. Higbie

B. Toor and Marcello

C. Kissinevskii

D. Danckwerts

1979. For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is___________________?
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A. Calculated

B. Unknown

C. Known

D. Not required

1980. The minimum liquid rate to be used in an absorber corresponds to an operating line_______________________?
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A. Of slope = 1

B. Of slope = 0.1

C. None of these

D. Tangential to the equilibrium curve
1981. Leaching rate is independent of the________________?
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A. None of these

B. Agitation

C. Temperature

D. Particle size

1982. In case of ______________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated?
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A. Azeotropic

B. Extractive

C. Molecular

D. Flash

1983. Lewis number (Le) is___________________?
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A. St Sh

B. Pr St

C. Sc Pr

D. Sh Pr

1984. The operating cost of a distillation column at minimum reflux ratio is____________________?
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A. Zero

B. Minimum

C. Maximum

D. Infinite

1985. Alcohol is dehydrated using _______________________ distillation?
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A. Azeotropic

B. Extractive

C. Molecular

D. Steam

1986. Most important factor to be considered in the selection of packings for absorbers is the ______________ of packing?
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A. Porosity

B. Size

C. Cost

D. Durability

1987. Flash distillation is suitable for the separation of components_________________?
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A. Which form maximum boiling azeotrope

B. Having very wide boiling points

C. Having very close boiling points

D. Which form minimum boiling azeotrope

1988. In rectifying section of a continuous distillation column, the____________________?
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A. None of these

B. Liquid is stripped of high boilers

C. Vapour is enriched with low boilers

D. Vapour is enriched with high boilers
1989. Which of the following is not a batch drier ?
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A. Vacuum shelf drier

B. Truck drier

C. Fluidised bed drier

D. Agitated pan drier

1990. Mass transfer co-efficient K according to penetration theory varies with mass diffusivity as____________________?
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A. D1.5

B. 1/D

C. D0.5

D. D

1991. Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapour-gas mixture is called the ________________ temperature?
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A. Adiabatic saturation

B. Wet-bulb

C. Dew point

D. Dry-bulb

1992. In a packed bed absorption column, the channelling will be noted by the ____________________?
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A. None of these

B. Increase in flow rate

C. Sharp drop in pressure drop

D. Sharp rise in pressure drop

1993. Which of the following decreases during evaporative cooling process with recirculated water supply ?
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A. Partial pressure of vapour

B. Wet bulb temperature

C. None of these

D. Relative humidity

1994. An air-water vapour mixture has a dry bulb temperature of 60C and a dew point temperature of 40C. The total pressure is 101.3 kPa and the vapour pressure of water at 40C and 60C 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__________________?
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A. 0.122

B. 0.079

C. 0.048

D. 0.152
1995. The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an _________________ law?
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A. Cubic

B. Exponential

C. Linear

D. Parabolic

1996. The reciprocal of stripping factor is termed as ________________________?
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A. Absorption factor

B. Relative volatility

C. Murphree efficiency

D. Selectivity index

1997. Equilibrium-moisture curves of different solids ____________________ ?
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A. Depend on the humidity of the gas

B. Are same

C. None of these

D. Are different
1998. Desirable value of absorption factor in an absorber is___________________?
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A. 1

B. > 1

C. < 1

D. 0.5

1999. Hydrogenation of oil is carried out in a/an _______________ in Vanaspati manufacturing plant?
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A. Bubble cap column

B. Packed tower

C. Agitated vessel

D. Sieve tray column

2000. Absorption with chemical reaction is involved in the removal of__________________?
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A. Ammonia from coke oven gas using refrigerated water

B. Tar from coke oven gas in primary gas coolers using chilled water

C. Carbon dioxide from gaseous stream using alkaline solution

D. Benzol from coke oven gas using solar oil/wash oil