chemical engineering Mcqs
2501. For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the ______________ filter?
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A. Plate & frame

B. Sand

C. Shell & leaf

D. Rotary vacuum

2502. Screw conveyors are________________?
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A. Suitable for sticky materials

B. All A., B. and C.

C. Run at very high rpm

D. Suitable for highly abrasive materials

2503. Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of ____________ mm?
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A. 0.007

B. 0.30

C. 0.014

D. 50

2504. Sedimentation on commercial scale occurs in____________________?
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A. Cyclones

B. Thickeners

C. Rotary drum filters

D. Classifiers

2505. ____________ mills fall in the category of tumbling mills ?
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A. Ball and pebble

B. Compartment

C. Rod and tube

D. All A., B. & C.
2506. For crushing of solids, the Rittingers law states that the work required for crushing is proportional to __________________?
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A. The size reduction ratio

B. None of these

C. The change in volume due to crushing

D. The new surface created
2507. Which of the following conveyors cannot be recommended for transportation of abrasive materials ?
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A. Apron conveyor

B. Flight conveyor

C. Belt conveyor

D. Chain conveyor

2508. The porosity of a compressible cake is _____________________?
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A. Minimum at the filter medium

B. Maximum at the filter medium

C. Same throughout the thickness of cake

D. Minimum at the upstream face

2509. Size reduction of the ______________ can be suitably done by ball mills, crushing rolls and rod mills?
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A. Asbestos & mica

B. Non-metallic ores

C. Metalliferous ores

D. Basic slags

2510. Which of the following relationships between co-efficient of friction (?) between rock & roll and a (half of the angle of nip) of the particle to be crushed is correct ?
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A. ? > tan 2?

B. ? ? tan ?

C. ? ? tan ?

D. ? > tan ?

2511. 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.
2512. Traces of liquid tar fog present in coke oven gas is separated using____________________?
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A. Strainer

B. Electrostatic precipitator

C. Cyclone separator

D. None of these

2513. For spheres, volume shape factor is given by____________________?
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A. AD/V

B. ? = (A/D2)

C. ?/6 = (V/D3)

D. 2? = (2A/D2)

2514. 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 high viscous suspension

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

C. Wet grinding in low viscous suspension

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

2515. On application of pressure to the equilibrium system, ice ? water; which of the following phenomenon will occur ?
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A. Water will evaporate

B. More water will be formed

C. More ice will be formed

D. Equilibrium will not be attained

2516. A compressible cake has the_________________?
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A. None of these

B. Maximum porosity at the filter medium

C. Same porosity throughout the cake thickness

D. Maximum porosity at the upstream side
2517. Gelatinous solid (which plug the septum) can be filtered by a _____________ filter?
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A. Sparkler

B. Vacuum leaf

C. Plate and frame

D. Pre-coat
2518. The capacity of a belt conveyor depends upon two factors. If one is the cross-section of the load, the other is the _____________ of the belt?
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A. Length

B. Thickness

C. Speed

D. None of these

2519. _____________ conveyors are also called scrapers?
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A. Apron

B. Screw

C. Helical flight

D. Both B. & C.
2520. Grizzlies are used for separating _____________ solids?
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A. Coarse

B. None of these

C. Fine

D. Any size

2521. Hot, lumpy & abrasive materials are best transported by using a/an ___________ conveyor ?
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A. Apron

B. Flight

C. Belt

D. Screw

2522. Which of the following is a batch sedimentation equipment ?
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A. Dust catcher

B. Filter thickener

C. Rotary sprayer scrubber

D. Dry cyclone separator

2523. All resistances during washing of cake _____________________?
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A. None of these

B. Increases

C. Remain constant

D. Decreases

2524. Fibrous material is broken by a__________________?
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A. Tube mill

B. Squirrel-cage disintegrator

C. Ball mill

D. Roll-crusher

2525. Compressibility co-efficient for an absolutely compressible cake is_______________?
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A. 0

B. 0 to 1

C. 1

D. ?

2526. Mesh indicates the number of holes per_________________?
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A. Square inch

B. Square foot

C. Linear inch

D. Linear foot

2527. The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is_________________?
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A. 1

B. None of these

C. 1.5

D. ?2

2528. Helical screw agitator is used for________________?
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A. None of these

B. Mixing liquids at very high temperature (> 250 C)

C. Mixing highly viscous pastes

D. Blending immiscible liquids

2529. Grinding characteristic of a material is given by its___________________?
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A. Shatter index

B. HGI

C. Angle of repose

D. Abrasion index

2530. Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, Vp = volume of one particle, ?= density of particles) ?
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A. Vp/m . ?

B. m . ?/Vp

C. m . Vp/?

D. m/? . Vp
2531. B.E.T. method can be used to determine the ___________________ of a porous catalyst?
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A. All A., B. and C.

B. Solid density

C. Pore volume

D. Surface area
2532. ____________ conveyor is the most suitable for long distance transportation of cold, nonabrasive granular/irregular shape/fine materials?
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A. Apron

B. Bucket

C. Screw

D. Belt
2533. 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.

2534. The study on washability of coal is done by using the _____________ technique?
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A. Heavy media separation

B. Tabling

C. Elutriation

D. None of these

2535. A tube mill compared to a ball mill__________________?
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A. Produces a coarser product

B. Has a higher length/diameter ratio

C. Uses much larger balls

D. Has a higher diameter/length ratio

2536. For a turbine agitated and baffled tank, operating at low Reynolds number (based on impeller diameter), the power number (Np) varies with NRe as_________________?
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A. Np ? NRe

B. Np ? constant

C. Np ? ?NRe

D. Np ? 1/NRe
2537. ______________ mean diameter of particles is given by ? (xi/Dpi ?)?
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A. Mass

B. Arithmetic

C. Volume

D. Volume surface

2538. Basic slag is not ground in_________________?
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A. Tube mills

B. Ball mills

C. Compartment mills

D. Jaw crushers
2539. Cartridge filters are termed as edge filters, because of the fact that the_________________?
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A. Disks have very sharp edge

B. Bulk of the solids are removed at the periphery of the disks

C. None of these

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

2540. ______________________ balls capable of grinding the feed in a ball mill gives the maximum efficiency ?
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A. Cast iron

B. Minimum size

C. Maximum size

D. Elliptical

2541. _____________________ baffles are provided in ball mills ?
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A. Horizontal

B. No

C. Only two

D. None of these

2542. Which of the following is the softest material ?
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A. Corundum

B. Feldspar

C. Talc

D. Calcite

2543. 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. 0.62

C. 0.58

D. 0.50
2544. Which of the following can be most effectively used for clarification of lube oil and printing ink ?
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A. Sharpies super-centrifuge

B. Sparkler filter

C. Pre-coat filter

D. Disc-bowl centrifuge

2545. Which of the following mineral dressing operations is termed as comminution?
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A. Spiralling

B. Panning

C. Tabling

D. None of these
2546. Grindability of a material does not depend upon its_____________________?
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A. Size

B. Hardness

C. Toughness

D. Elasticity

2547. Screen capacity is not a function of__________________?
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A. Atmospheric humidity

B. Screening surface

C. Screening mechanism

D. Its openings size

2548. The work index in Bonds law for crushing of solids has the following dimensions__________________?
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A. kWh/ton

B. kWh.m1/2/ton

C. No units (dimensionless)

D. kW/ton

2549. Stamp mills are generally used for crushing__________________?
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A. Iron ores

B. Gold ores

C. Talc

D. Diamond

2550. In froth floatation, chemical agent added to cause air adherence is called___________________?
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A. Collector

B. Activator

C. Modifier

D. Frother