chemical engineering mechanical operations MCQs – Page 7

Practise multiple-choice questions from chemical engineering mechanical operations for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering mechanical operations Mcqs

121. Which of the following is not used as a filter medium in case of corrosive liquids?
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A. Metal cloth of monel or stainless steel

B. Glass cloth

C. Cotton fabric

D. Nylon

122. Cumulative analysis for determining surface is more precise than differential analysis, because of the_______________?
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A. Fact that screening is more effective

B. Assumption that all particles in a single fraction are equal in size, is not needed

C. Assumption that all particles in a single fraction are equal in size

D. None of these

123. The crushed material received for separation is called feed or_________________?
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A. Heading

B. Tailing

C. Concentrate

D. Middling

124. Grinding characteristic of a material is given by its___________________?
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A. HGI

B. Angle of repose

C. Shatter index

D. Abrasion index

125. Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called__________________?
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A. Clarification

B. Thickening

C. Froth floatation

D. Classification

126. In case of a ball mill ?
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A. None of these

B. Coarse feed requires a larger ball

C. Operating speed should be more than the critical speed

D. Fine feed requires a larger ball

127. If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the_________________?
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A. Linear speed of the basket is doubled

B. Linear speed of the basket is halved

C. Capacity of centrifuge is increased

D. Centrifugal force is doubled

128. Which of the following achieves the least reduction ratio for a given feed size ?
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A. Gyratory crusher

B. Jaw crusher

C. Cone crusher

D. Roll crusher

129. Rittingers number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittingers number of a material indicates its________________?
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A. High power consumption in grinding

B. Easier grindability

C. None of these

D. Poor grindability

130. A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is_____________?
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A. 0.1

B. None of these

C. 0.4

D. 0.6

131. Paddle agitator_________________?
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A. None of these

B. Produces axial flow

C. Moves at very high speed

D. Is suitable for mixing low viscosity liquids

132. In classification, particles are said to be equal settling, if they have the same terminal velocities in the_______________?
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A. Different fluids

B. Same fluid

C. Same field of force

D. Both B. and C.

133. In a grinding operation, the limiting particle size is the size of the _______________ particle in the sample?
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A. Smallest

B. Either A. or B.

C. Largest

D. Neither A. nor B.

134. Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator ?
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A. Cresylic acid

B. Calcium carbonate

C. Copper sulphate

D. Sodium carbonate

135. The most suitable equipment for the transportation of 200 mesh size particles is a _______________?
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A. Screw conveyor

B. Bucket elevator

C. Pneumatic conveyor

D. Belt conveyor

136. Removal of activated carbon from glycerine is done by _________________?
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A. Rotary vacuum filter

B. Batch basket centrifuge

C. None of these

D. Plate and frame filter

137. Pine oil used in froth floatation technique acts as a/an_____________________?
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A. Modifier

B. Frother

C. Collector

D. Activator

138. _______________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals?
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A. Selectivity index

B. Separation efficiency

C. Concentration ratio

D. None of these

139. ______________ are used for the separation of coarse particles from a slurry of fine particles?
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A. Classifiers

B. Decanters

C. Hydrocyclones

D. Thickeners

140. Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle)?
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A. V/D.S

B. 6.V/D.S

C. V/6D.S

D. D.S/V

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