chemical engineering Mcqs
2551. Temperature of the product during ultrafine grinding_____________________?
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A. Decreases

B. Increases

C. Remain constant

D. May increase or decrease; depends on the material being ground

2552. Filtration rate does not depend upon the________________?
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A. Pressure drop & area of filtering surface

B. Properties of the cake & the filtrate

C. None of these

D. Resistance of the cake & the septum

2553. The unit of specific cake resistance is______________________?
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A. cm/gm

B. cm/gm2

C. gm/gm

D. gm/cm2
2554. Filter medium resistance is that offered by the__________________?
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A. Embedded particles in the septum

B. None of these

C. Filter cloth and the embedded particle collectively

D. Filter cloth

2555. Limestone is normally crushed in a _____________________?
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A. Hammer crusher

B. Ball mill

C. Tube mill

D. Roll crusher

2556. In a roll crusher, both the rolls_________________?
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A. Run either at the same or different speeds

B. Have the same diameter

C. Are rotated towards each other

D. All A., B. and C.
2557. If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is ?s is defined by________________?
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A. ?s = dpSp/Vp

B. ?s = 6 dpSp/Vp

C. ?s = Vp/dpsp

D. ?s = 6 Vp/dpsp
2558. The value of n for a chemical reaction A ? B, whose reaction rate is ? CA n, will be _______________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled?
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A. 3

B. 1

C. 0

D. 2

2559. Which of the following is a coarse crusher ?
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A. Toothed roll crusher

B. Smooth roll crusher

C. Gyratory crusher

D. Tube mill

2560. For Indian standard (IS) screens, the mesh number is equal to its aperture size expressed to the nearest deca-micron (0.01 mm). Aperture width of IS screen of mesh number 50 will be approximately _____________ microns?
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A. 5

B. 5000

C. 50

D. 500
2561. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ?L) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ? and no cake is formed. The initial pressure drop during filtration is ___________________?
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A. w2 . ?2 . ?L

B. w2 . ??L (2R + ?)

C. w2 . R2 . ?L

D. w2 . R . ?L(R + 2?)

2562. _____________ mills are termed as disintegrators?
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A. Compartment

B. Pebble

C. Cage

D. All tumbling

2563. For raschig rings, the sphericity is_____________________?
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A. 0.5

B. 1

C. < 1

D. ?3

2564. Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ? = bulk density of material, kg/m3) ?
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A. 3.6 W.D.V.?

B. 3.6 D.V.?

C. 3.6 W.D.V

D. 3.6 W.V.?

2565. For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is__________________?
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A. 2250

B. 1125

C. 230

D. 460

2566. For the preliminary breaking of hard rock, we use a____________________?
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A. Gyratory crusher

B. Squirrel-cage disintegrator

C. Ball mill

D. Tube mill

2567. A _____________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end?
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A. Pebble

B. Rod

C. Tube

D. Compartment
2568. Separation of solid particles based on their densities is called_________________?
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A. Sizing

B. Sorting

C. Dispersion

D. Clarification

2569. Gold ore concentration is mostly done using___________________?
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A. Froth floatation

B. Jigging

C. Tabling

D. Elutriation

2570. Separation of materials into products based on the difference of their sizes is called___________________?
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A. Flocculation

B. Sorting

C. Classification

D. Sizing
2571. Size reduction mechanism used in Jaw crushers is__________________?
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A. Impact

B. Attrition

C. Cutting

D. Compression
2572. Supporting legs of a plate and frame filter is normally made of________________?
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A. Wooden plank

B. Stainless steel

C. High speed steel

D. Cast iron
2573. Apron conveyors are used for ___________________ ?
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A. None of these

B. Heavy loads & long runs

C. Small loads & long runs

D. Heavy loads & short runs
2574. Volume change for unimolecular type first order reaction as shown in the bellow figure, increases _____________ with time?
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A. Parabolically

B. Exponentially

C. Linearly

D. Logarithmically

2575. For the transportation of ultrafine particles, the equipment used is a ____________ conveyor?
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A. None of these

B. Screw

C. Pneumatic

D. Belt

2576. Ball mills and tube mills with flint or porcelain balls are used for size reduction of_______________?
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A. Limestone

B. Rubber

C. Asbestos

D. Non-metallic ores
2577. Mechanical conveyors which push the material along an endless trough or tube are called scrappers. Which of the following conveying equipments comes under the category of scrappers? ?
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A. Bucket conveyor

B. Flight conveyor

C. Screw conveyor

D. Both B. and C.
2578. Work index is defined as the_________________?
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A. product passes through a 100 micron screen</strong>

B. Energy needed to crush one ton of feed to 100 microns

C. Gross energy (kWh/ton of feed) needed to reduce very large feed to such a size that 80% of

D. ses a 200 mesh screen

E. Energy (kWh/ton of feed) needed to crush small feed to such a size that 80% of the product

F. Energy needed to crush one tonne of feed to 200 microns

2579. Colloid mills achieve size reduction mainly by___________________?
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A. Attrition

B. Impact

C. Cutting

D. Compression

2580. 200 mesh screen means 200 openings per_____________________?
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A. cm

B. inch

C. cm2

D. inch2

2581. The first order series reaction as shown in the bellow figure is conducted in a batch reactor. The initial concentrations of A, B and C (CA0, CB0, CC0 respectively) are all non-zero. The variation of CB with reaction time will not show a maximum, if___________________?
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A. CA0 > CB0

B. k CA0 > k2.CB0

C. CB0 > CA0

D. k2 CB0 > k1 CA0
2582. To remove very small amount of tiny solid impurities from liquid, we use a_____________________?
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A. Pressure filter

B. Vacuum filter

C. Coagulant

D. Centrifugal filter

2583. Balls for ball mills are never made of_________________?
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A. Lead

B. Cast iron

C. Alloy steel

D. Forged/cast steel

2584. Which of the following is not an ultrafine grinder (colloid mill) ?
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A. Agitated mills and fluid energy mills

B. Toothed roll crusher

C. Hammer mills with internal classification

D. Micronizers

2585. Highly viscous liquids & pastes are agitated by________________?
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A. None of these

B. Turbine agitators

C. Propellers

D. Multiple blade paddles
2586. _______________ mill is normally used for grinding of talc?
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A. Compartment

B. Tube

C. Pebble

D. Ring-roll
2587. According to Bond crushing law, the work required to form particle of size D from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively) ?
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A. (S/V)f

B. (S/V)2p

C. ?(S/V)p

D. (S/V)p

2588. For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a__________________?
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A. Buhrstone mill

B. Ball mill

C. Hammer mill

D. Crushing rolls

2589. The reduction ratio for fine grinders is_____________?
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A. 10-May

B. 20-40

C. 20-Oct

D. As high as 100
2590. According to Taggarts rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than_______________?
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A. 0.184

B. 0.00184

C. 0.0184

D. 1.84

2591. Ultrafine grinders operate principally by_________________?
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A. Impact

B. Cutting action

C. Slow compression

D. Attrition
2592. Weber number is significant and is concerned with the_________________?
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A. Dispersion of liquid in liquid

B. Suspension of solid in liquid

C. Solid-liquid mixing

D. Liquid-liquid mixing

2593. Two particles are called to be equal settling, if they are having the same ?
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A. Terminal velocities in the same fluid & in the same field of force

B. None of these

C. Size

D. Specific gravity

2594. Gravity settling process is not involved in the working of a________________?
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A. Dorr-thickener

B. Sedimentation tank

C. Classifier

D. Hydrocyclone
2595. The term angle of nip is concerned with the operation of the ____________ crushers?
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A. Jaw

B. Gyratory

C. None of these

D. Roll
2596. Addition of filter aid to the slurry before filtration is done to _______________ of the cake?
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A. Decrease the compressibility co-efficient

B. Increase the compressibility co-efficient

C. Decrease the porosity

D. Increase the porosity
2597. Xanthates are used in the froth floatation process as a/an _______________________?
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A. Conditioner

B. Activator

C. Frother

D. Collector
2598. The operating speed of a ball mill should be ______________ the critical speed?
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A. Much more than

B. At least equal to

C. Less than

D. Slightly more than

2599. Froth floatation is the most suitable for treating ____________________?
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A. Quartzite

B. Iron ores

C. Sulphide ores

D. None of these

2600. If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the_________________?
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A. Centrifugal force is doubled

B. Linear speed of the basket is halved

C. Capacity of centrifuge is increased

D. Linear speed of the basket is doubled