chemical engineering mechanical operations MCQs – Page 18

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 Review each marked answer and report any item that may be outdated or unclear.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
341. The study on washability of coal is done by using the _____________ technique?
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A. Elutriation

B. None of these

C. Tabling

D. Heavy media separation
342. Energy consumption in a crusher decreases with increase in the________________________?
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A. Size of the product (at constant feed size)

B. Capacity of the crushing machine

C. Size of feed (at constant reduction ratio)

D. All A., B. & C.
343. Pick out the wrong statement ?
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A. 200 mesh screen has 200 openings per linear cm

B. Hammer crushers operate by impact action

C. Standard screens have circular opening

D. With increase in mesh number of screens, their diameter in microns decreases

344. Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ?
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A. Wet grinding in low viscous suspension

B. Dry grinding of large particles (upto 1.25 cms)

C. Dry grinding of large particles in un-baffed mills

D. Wet grinding in high viscous suspension

345. The operating speed of a ball mill should be ______________ the critical speed?
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A. At least equal to

B. Slightly more than

C. Much more than

D. Less than
346. Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of_____________________?
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A. Cams or eccentric shafts

B. Electromagnets

C. Unbalanced flywheels

D. Either A., B. or C.
347. Cake resistance is___________________?
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A. Decreased with the time of filtration

B. Important in the beginning of filtration

C. None of these

D. Independent of pressure drop

348. Pick out the wrong statement?
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A. Capacity of crusher in choke feeding is increased

B. meter, in which the area beneath the curve represents the surface

C. Cumulative analysis for determining surface area is preferred over differential analysis,

D. ause of the assumption that all particles in a simple fraction equal in size is not needed

E. Rolling of pebbles/balls from top to bottom of the heap in tumbling mills is called cascading

F. throwing of the balls through the air to the toe of the heap is called cataracting

349. Filtration rate does not depend upon the________________?
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A. None of these

B. Properties of the cake & the filtrate

C. Pressure drop & area of filtering surface

D. Resistance of the cake & the septum

350. Use of baffles in agitators help in minimising the ______________ tendency?
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A. Swirling

B. Vortexing

C. Both A. & B.

D. Neither A. nor B.

351. Which of the following is a coarse crusher ?
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A. Smooth roll crusher

B. Tube mill

C. Gyratory crusher

D. Toothed roll crusher

352. Close circuit grinding by a ball mill with air sweeping employs a _______________________?
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A. Classifier

B. Cyclone separator between mill & classifier

C. Both A. & B.

D. Neither A. nor B.

353. Sauter mean diameter is the same as the ______________ mean diameter?
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A. Geometric

B. Arithmetic

C. Volume-surface

D. Mass

354. Solid particles separation based on the difference in their flow velocities through fluids is termed as the__________________?
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A. Classification

B. Sedimentation

C. Elutriation

D. Clarification

355. A tube mill compared to a ball mill__________________?
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A. Has a higher diameter/length ratio

B. Uses much larger balls

C. Produces a coarser product

D. Has a higher length/diameter ratio
356. Cartridge filters are termed as edge filters, because of the fact that the_________________?
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A. Bulk of the solids are removed at the periphery of the disks

B. Solids are not deposited at the edge of the disk

C. None of these

D. Disks have very sharp edge

357. The unit of specific cake resistance is______________________?
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A. cm/gm2

B. gm/gm

C. gm/cm2

D. cm/gm

358. Moisture can be removed from lubricating oil using_________________?
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A. Tubular centrifuge

B. Clarifier

C. Sparkler filter

D. Vacuum leaf filter

359. Screen capacity is proportional to (where, S = screen aperture)____________________?
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A. 1/S

B. S2

C. S

D. ?S

360. Tank filter (e.g., Nutsche filter) is___________________?
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A. A leaf filter

B. A continuous filter

C. A high pressure filter

D. Used for small scale filtration work