chemical engineering mechanical operations MCQs – Page 13

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 Review each marked answer and report any item that may be outdated or unclear.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
241. Which of the following is the hardest material ?
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A. Gypsum

B. Corundum

C. Calcite

D. Quartz

242. Where the density difference of the two liquid phase to be separated is very small (as in milk cream separator), the most suitable separator is a____________________?
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A. Batch basket centrifuge

B. Sharpies super-centrifuge

C. Sparkler filter

D. Disc bowl centrifuge
243. Use of grinding aids is done in _______________ grinding?
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A. Wet

B. Intermediate

C. Ultrafine

D. Dry
244. _____________ mills are termed as impactors?
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A. Hammer

B. Cage

C. None of these

D. Rolling-compression

245. During agitation of liquids, power consumption during laminar flow is not proportional to the ________________?
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A. Cube of impeller diameters

B. Square of rotational speed

C. Density of the liquid

D. Viscosity of the liquid

246. For a non-spherical particle, the sphericity__________________?
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A. Is defined as the ratio of surface area of a sphere having the same volume as the particle to the

B. ume of the particle

C. ual surface area of the particle</strong>

D. Has the dimension of length

E. Is the ratio of volume of a sphere having the same surface area as the particle to the actual

F. Is always less than 1

247. Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation ?
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A. Crush shaft

B. Jaw plates

C. Toggles

D. Check plates

248. The controlling resistance in a rotary drum vacuum filter is the ________________ resistance?
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A. None of these

B. Piping

C. Filter medium

D. Cake
249. About 2-3 hp, power per gallon of a thin liquid provides vigorous agitation in an agitator. Power number in agitation is given by __________________?
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A. P. gc/n3. D2. ?

B. P. gc. ?/?2

C. P. gc/n2. D2. ?

D. n3. D3. ?/P. gc

250. Solid particles of different densities are separated by _____________________?
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A. Sorting classifier

B. Filters

C. Cyclones

D. Thickness

251. If a force greater than that of gravity is used to separate solids & fluids of different densities, the process is termed as the __________________?
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A. Dispersion

B. Flocculation

C. Centrifugation

D. Sedimentation

252. In case of a hammer crusher, the final product size depends on the____________________?
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A. All A., B. and C.

B. Feed rate

C. Clearance between hammer & grinding plates

D. Rotor speed

253. Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with ______________ to get the same for dry grinding?
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A. 0.5

B. 1

C. 4.34

D. 1.34
254. The capacity of a pneumatic conveying system depends upon the ______________________?
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A. All A., B. and C.

B. Diameter of the conveying line

C. Bulk density of materials

D. Pressure of the conveying air

255. 200 mesh sieve size corresponds to _____________ microns?
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A. 154

B. 74

C. 200

D. 24

256. Ball mill is used for__________________?
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A. Fine grinding

B. Crushing

C. Attrition

D. Coarse grinding

257. A sand mixture was screened through a standard 10-mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is_________________?
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A. 0.68

B. 0.50

C. 0.58

D. 0.62

258. A cottrell precipitator makes use of the ______________ for dusty air cleaning?
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A. Alternating current

B. Corona discharge

C. None of these

D. Electric spark

259. The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is Wi, then the same for open circuit grinding will be_________________?
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A. 3.34 Wi

B. Wi

C. 0.5 Wi

D. 1.34 Wi
260. Size reduction of fibrous materials like wood, asbestos, mica etc. is done by a disintegrator exemplified by the _________________?
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A. Stamp mill

B. Bradfords breaker

C. Cage mill

D. Blake jaw crusher