chemical engineering mechanical operations MCQs – Page 14

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 Review each marked answer and report any item that may be outdated or unclear.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
261. In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of _______________ crushing?
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A. Secondary

B. Ultrafine

C. Fine

D. Primary

262. For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter) ?
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A. AD/V

B. None of these

C. ? = (A/D2)

D. ?/6 = (V/D3)

263. Specific surface area is the surface area of a unit _______________ of materials?
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A. Either A. or B.

B. Volume

C. Neither A. nor B.

D. Weight

264. Velocity of a small particle of diameter Dp at a distance r from the rotational axis of a cyclone rotating at an angular speed ? is given by (the other symbols are as per standard notation) ?
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A. [(DP2/18). (?s ?/?)] ?2r

B. [(DP2/18). (?s ?/?)] ?2r

C. [(DP/18). (?s ?/?)] ?2r2

D. [(DP/18). (?s ?/?)] ?2r

265. The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a __________________?
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A. Sharpies centrifuge

B. None of these

C. Boundary mixer

D. Propeller agitator

266. Maximum size reduction in a ball mill is done by the, ______________ action?
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A. Cutting

B. Impact

C. Attrition

D. Compression

267. Which of the following is not used as a surface active agent in a flocculation operation ?
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A. Alumina

B. Quartz

C. Sodium silicate

D. Lime

268. _____________ Centrifuge is normally used in sugar mills?
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A. Suspended batch basket

B. Disc-bowl

C. Tubular bowl

D. Perforated horizontal basket continuous

269. Mixer used for rubber compounding is__________________?
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A. Pug mill

B. Muller mixer

C. Banbury internal mixer

D. mixer-extruder

270. Separation of materials into products based on the difference of their sizes is called___________________?
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A. Sizing

B. Flocculation

C. Classification

D. Sorting

271. Balls for ball mills are never made of_________________?
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A. Alloy steel

B. Forged/cast steel

C. Cast iron

D. Lead
272. For spheres, volume shape factor is given by____________________?
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A. ? = (A/D2)

B. 2? = (2A/D2)

C. AD/V

D. ?/6 = (V/D3)
273. Grizzlies are used for separating _____________ solids?
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A. Coarse

B. Any size

C. None of these

D. Fine
274. In a mixer, the quantity, (v. L/D) is termed as __________ number (where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing) ?
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A. Schmidt

B. Weber

C. Brinkman

D. Peclet
275. Diatomaceous earth is a/an_________________?
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A. Catalyst

B. Explosive

C. Filter aid

D. Filter medium

276. A pebble mill_________________?
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A. Is a ball mill

B. Employs flints or ceramic pebbles as the grinding medium

C. Is a tube mill lined with ceramic or other non-metallic liner

D. Both B. and C.
277. What is the selectivity index, if the grade of tailings & concentrate is the same ?
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A. 1

B. 0

C. 0.5

D. ?

278. Metallic wire mesh is used as a filtering medium for the separation of dust from dust laden gas in case of a/an________________?
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A. Hydrocyclones

B. Air filter

C. Venturi scrubber

D. Bag filter

279. Mixing of light fine powder such as insecticides is done by____________________?
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A. Impact wheels

B. Pug mill

C. Kneader

D. Banbury mixer

280. Production rate _____________ with increased fineness, with a given energy input to the size reduction machine?
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A. May increase or decrease; depends on the machine

B. Remains unchanged

C. Decreases

D. Increases