chemical engineering mass transfer Mcqs
101. Minimum reflux ratio in a distillation column results in__________________?
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A. Maximum condenser size

B. Minimum number of trays

C. Minimum reboiler size

D. Optimum number of trays

102. The diffusivity D. in a binary gas mixture is related to the pressure (P) as___________________?
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A. D ? 1/P

B. D ? 1/P1.5

C. D ? 1/P0.5

D. D ? P0.5

103. Which of the following is directly concerned with Psychrometry ?
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A. Lewis relationship

B. Dean number

C. Galileo number

D. Weber number

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

B. Equal to

C. More than

D. Less than
105. A binary mixture of benzene and cyclohexane is separated by___________________?
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A. Solvent extraction

B. Ordinary distillation

C. Extractive distillation

D. Flash vaporisation

106. Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.) ?
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A. (1 + Ri) = Ro/Ri

B. (1 + Ro) = Ro/Ri

C. (1 Ri) = Ro/Ri

D. (1 Ro) = Ro/Ri

107. Dimension of mass diffusivity is the same as that of_____________________?
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A. Kinematic viscosity

B. Pressure

C. Dynamic viscosity

D. Surface tension

108. Laboratory determination of the diffusivity of vapor is done by __________________ method?
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A. Wetted wall column

B. Winkelmanns

C. Wikes

D. Gillilands

109. For absorbing a sparingly soluble gas in a liquid, the_____________________?
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A. Liquid side coefficient should be increased

B. Liquid side co-efficient should be decreased

C. Gas side co-efficient should be decreased

D. Gas side co-efficient should be increased

110. Leaching of uranium ore and gold ore is done in_____________________?
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A. Pachuca tanks

B. Centrifugal extractor

C. Bollman extractor

D. None of these

111. The apex of an equilateral-triangular coordinate (in ternary liquid system) represents a/an ___________________?
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A. Binary mixture

B. Ternary mixture

C. Insoluble binary system

D. Pure component
112. In case of constant underflow extraction operation, the _______________________ at all solute concentration?
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A. Solids are drained to the same extent

B. Ratio of the insoluble to solution is constant

C. Both A. & B.

D. Neither A. nor B.

113. Which of the following is an undesirable property in a tower packing ?
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A. Large weight of liquid retained

B. Large free cross-section

C. Large surface per unit volume

D. Low weight per unit volume

114. In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be_____________________?
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A. 2 metres above the ground

B. At ground level

C. 10 metres above ground

D. 5 metres above ground

115. In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in_________________?
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A. Maintaining the concentration difference between the two phases

B. All A , B & C.

C. Reducing the axial mixing

D. Increasing the rate of extraction

116. The drying time between fixed moisture content within diffusion controlled falling rate period is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid) ?
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A. T2

B. ?T

C. T3

D. T

117. Mass transfer co-efficient K according to penetration theory varies with mass diffusivity as____________________?
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A. 1/D

B. D1.5

C. D0.5

D. D

118. For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a _______________ of the equilateral triangular co-ordinates?
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A. Binary mixture is represented by any point inside

B. Ternary mixture is represented by the sides

C. Binary mixture is represented by the apex

D. Pure component is represented by the apex
119. Raoults law does not apply, when the___________________?
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A. Component molecules are non-polar

B. Size of component molecules are not equal

C. Chemical combination or molecular association between unlike molecules takes place in the

D. Attractive forces between like and unlike molecules in the solution are approximately equal

E. mation of solution

120. The ratio of Murphree plate efficiency to point efficiency is 1 in a ______________________ flow model?
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A. Plug

B. Perfectly mixed

C. Both A. & B.

D. Neither A. nor B.

121. 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___________________?
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A. 1.24

B. 1.94

C. 1.04

D. 0.54

122. Dorr thickener is an equipment used for______________________?
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A. Clarification

B. Leaching

C. Sedimentation

D. Classification

123. Dried finished product sampled from various parts of a ________________ dryer exhibits nonuniformity in the moisture content?
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A. None of these

B. Tray

C. Rotary

D. Freeze

124. In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed____________________?
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A. q > 1

B. q = 1

C. q < 1

D. q = 0

125. Pick out the wrong statement ?
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A. Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure

B. stance

C. In case of gas absorption, HETP is equal to HTU, when both the operating line & the

D. ilibrium lines are parallel

E. Hatta number is important in case of gas absorption with chemical reaction

F. In actual practice, absorption is an endothermic process, while stripping is an exothermic
126. Coffee is prepared from coffee beans by leaching with____________________?
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A. Hot water

B. Dilute hot caustic solution

C. Cold water

D. Naphtha

127. In case of unsaturated air_________________?
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A. Dew point < wet bulb temperature

B. Wet bulb temperature < dry bulb temperature

C. Both A. and B.

D. Neither A. not B.

128. The Hatta number is important in_________________?
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A. Gas absorption without chemical reaction

B. Binary distillation

C. Multi-component distillation

D. Gas absorption with chemical reaction
129. The process employing desorption of the absorbed solute by a solvent is called____________________?
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A. Osmosis

B. Reverse osmosis

C. Elution

D. Sublimation

130. A 25 cm 25 cm 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m 1m 1cm flat sheet of the same material is to be dried from one side only. Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is ____________________?
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A. 2000

B. 2500

C. 1000

D. 1500

131. The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2/m3) ?
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A. 1200

B. 500

C. 800

D. 900

132. In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is_________________?
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A. Called integral heat of adsorption

B. Equal to the heat of formation of surface compound

C. Equal to the heat of wetting

D. Zero

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

B. Durability

C. Size

D. Cost

134. Henrys law states that the ________________________?
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A. Partial pressure of a component over a solution is proportional to the mole fraction in the

B. our

C. Partial pressure is equal to the product of the mole fraction and total pressure

D. uid</strong>

E. Vapour pressure is equal to the product of the mole fraction and total pressure

F. Partial pressure of a component over a solution is proportional to its mole fraction in the
135. The temperature of water cooled in cooling tower is always _________________ temperature of entering air?
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A. Less than the wet bulb

B. More than the wet bulb

C. Equal to the wet bulb

D. Equal to the dry bulb

136. High pressure at the bottom of a distillation tower handling heat sensitive materials results in _____________________?
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A. Thermal decomposition of bottoms

B. Erosion of the tower

C. Increased relative volatility

D. Very efficient operation

137. Use of packed towers for distillation is generally limited to the__________________?
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A. Multi-component distillation

B. Vacuum distillation

C. High pressure operation

D. Small sizes
138. Pick out the wrong statement?
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A. Mass transfer co-efficient does not account for gas-liquid diffusion

B. Contacting cold vapor-gas mixture with hot liquid exemplifies humidification process

C. Diffusion co-efficient and mass transfer co-efficient are not same in any mass transfer

D. Contacting cold liquid with warm vapor-gas mixture exemplifies dehumidification process

E. ration

139. Use of packed towers for distillation is generally limited to the____________________?
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A. Multi-component distillation

B. Vacuum distillation

C. Small sizes

D. High pressure operation

140. Laboratory determination of the diffusivity of vapor is done by ______________ method?
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A. Gillilands

B. Winkelmanns

C. Wikes

D. Wetted wall column

141. Molecular sieves are regenerated by heating to ______________ C?
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A. > 500

B. < 150

C. > 1000

D. 200-330
142. For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause ____________________ plate requirement?
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A. Major decrease in the number of

B. None of these

C. No change in theoretical

D. Marginal decrease in the number of
143. In a gas-liquid absorption column, for obtaining the maximum absorption efficiency___________________?
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A. Liquid stream should be distributed uniformly

B. Gas stream should be distributed uniformly

C. Both gas as well as liquid streams should be distributed uniformly

D. By passing should be completely avoided

144. The value of L/mG ratio for economical absorption operation ranges from _____________________?
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A. 0.5 to 0.8

B. 0.8 to 1.2

C. 2.5 to 3.5

D. 1.25 to 2.0
145. Leaching of uranium ore and gold ore is done in________________________?
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A. None of these

B. Pachuca tanks

C. Centrifugal extractor

D. Bollman extractor

146. 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) ?
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A. Kc = Kp = Km

B. None of these

C. Kc = Kp . RT = Km . RT/p

D. Kc = Kp/RT = Km . RT/P

147. In triangular co-ordinates, the ternary composition point falls ___________________ of the triangle?
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A. In the corners

B. On the sides

C. Inside

D. None of these

148. 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.

149. Swenson-Walker crystalliser is a __________________ unit ?
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A. Cooling (adiabatic)-cum-evaporation

B. Batch

C. Semi-batch

D. Continuous
150. What is the degree of freedom of an absorption process in which only one component is transferred between phases ?
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A. 2

B. 3

C. 4

D. 1