chemical engineering Mcqs
2301. With increase in the capacity of screens, the screen effectiveness__________________?
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A. Increases

B. Decreases

C. Decreases exponentially

D. Remains unchanged

2302. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG ______________ the absorption factor?
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A. Increases with increase in

B. Is one at unity value of

C. Both A. and B.

D. Neither A. nor B.

2303. During the washing of cake_________________?
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A. All the resistances are constant

B. Cake resistance decreases

C. Filter medium resistance decreases

D. Filter medium resistance increases

2304. Which of the following is used for primary crushing of very hard lumpy materials ?
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A. Gyratory crusher

B. Ball mill

C. Toothed roll crusher

D. Tube mill

2305. In case of absorption with exothermic reaction, for fluids having ___________________?
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A. Pr = Sc; percentage change in heat and mass transfer flux will be the same for a given change

B. the degree of turbulence

C. Pr = Sc = 1; total mass, momentum and thermal diffusivity will be the same

D. Both A. and B.

E. Pr = Sc; there wont be any change in heat and mass transfer flux with changes in degree of

F. bulence

2306. To remove dirt from the flowing fluid, we use a ____________________?
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A. Gravity settler

B. Coagulant

C. Strains

D. Clarifier

2307. Screen capacity is expressed in terms of____________________?
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A. tons/hr

B. tons/ft2

C. Both A. & B.

D. tons/hr-ft2
2308. Separation of isotopes is generally done using a/an _______________ centrifuge?
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A. Ultra

B. Disk-bowl

C. Both A. & B.

D. Neither A. nor B.

2309. The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is_______________?
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A. 1.5

B. ?3

C. 2

D. ?2
2310. Occurrence of case hardening during drying of a high moisture solid cake _______________ the drying rate?
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A. Exponentially increases

B. Does not affect

C. Increases

D. Decreases
2311. Tube mill compared to ball mill_______________________?
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A. Produces finer products

B. Uses smaller balls

C. Is long in comparison with its diameter

D. All A., B. & C.
2312. When the temperature and humidity of air is low, we usually use _______________ draft cooling tower?
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A. None of these

B. Natural

C. Induced

D. Forced

2313. Which of the following equations is Rittingers crushing law? (Where P = power required by the machine, m = feed rate, k = a constant, D? sa & D? sb = volume surface mean diameter of feed & product respectively) ?
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A. P/m = K/ ?Dp

B. P/m = K . ln D? sa/D? sb

C. P/m = K . (1/ D? sb 1/D? sa)

D. None of these

2314. The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to___________________?
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A. N1

B. N2

C. N

D. N3

2315. Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1F is called the________________?
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A. Specific heat

B. Humid heat

C. Sensible heat

D. Latent heat

2316. If G = insoluble gas in gas stream and L = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is___________________?
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A. G/L

B. Always < 1

C. None of these

D. L/G
2317. 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. Centrifugation

B. Sedimentation

C. Flocculation

D. Dispersion

2318. For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid ?
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A. Kozeny-Carman equation

B. None of these

C. Levas equation

D. Blake-Plummer equation

2319. There is practically no alternative/competitor to _________________ in the beneficiation treatment of sulphide ores?
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A. Tabling

B. Froth floatation

C. Jigging

D. Classification

2320. The filtrate flow rate in constant pressure filtration___________________?
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A. Continuously decreases

B. Continuously increases

C. Remain constant throughout

D. May increase or decrease; depends on the pressure

2321. Filtrate flow rate in case of a rotary drum vacuum filter (in which Rm < < Rc) is proportional to ____________ and the cycle time (where, ? = filtrate viscosity Rm = filter medium resistance Rc = cake resistance)?
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A. 1/?

B. ??

C. 1/??

D. 1/?2

2322. _______________ centrifuge is the most suitable for separation of non-friable crystals?
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A. Disc-bowl

B. Suspended batch basket

C. Perforated horizontal basket continuous

D. Tubular bowl

2323. Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in ____________________?
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A. Viscosity with concentration

B. Degree of ideality of the solution

C. Both A. and B.

D. Neither A. nor B.

2324. For efficient grinding, ball mills must be operated__________________?
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A. At a speed less than the critical speed

B. At a speed more than the critical speed

C. With minimum possible small balls

D. At a speed equal to the critical speed

2325. Vacuum filter is most suitable for the_______________?
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A. Removal of fines from liquid

B. Liquids of very high viscosity

C. Liquids having high vapour pressure

D. None of these
2326. Specific surface area is the surface area of a unit _______________ of materials?
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A. Volume

B. Either A. or B.

C. Weight

D. Neither A. nor B.

2327. Separation of materials of the same density based on their sizes by using then-different rates of flow is called__________________?
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A. Sorting

B. Elutriation

C. Sizing

D. Flocculation

2328. Overall efficiency of the distillation column is _____________________?
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A. The ratio of number of ideal plates to actual plates

B. The ratio of number of actual plates to ideal plates

C. Same as the Murphree efficiency

D. Always more than the point efficiency

2329. Which of the following mechanical conveyors does not come under the division carriers? ?
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A. Apron conveyor

B. Bucket elevator

C. Belt conveyor

D. Screw conveyor
2330. CO2 can be absorbed by____________________?
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A. Hot cupric oxide

B. Alumina

C. Cold Ca(OH)2

D. Heated charcoal
2331. With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge________________?
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A. Increases

B. Decreases

C. Remains constant

D. Increases linearly

2332. The most suitable equipment for the transportation of 200 mesh size particles is a _______________?
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A. Pneumatic conveyor

B. Bucket elevator

C. Belt conveyor

D. Screw conveyor

2333. The critical speed of a trommel (N) is related to its dia D. as _____________________?
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A. N ? 1/?D

B. N ? D

C. N ? ?D

D. N ? 1/D

2334. The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the _____________ filter?
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A. Plate & frame

B. Sand

C. Rotary

D. Vacuum

2335. As particle size is reduced__________________?
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A. Screening becomes progressively easier

B. Screening becomes progressively more difficult

C. None of these

D. Capacity and effectiveness of the screen is increased

2336. In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the ________________ crushing?
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A. Ultrafine

B. Fine

C. Secondary

D. Primary
2337. Ball mill is used for__________________?
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A. Fine grinding

B. Coarse grinding

C. Attrition

D. Crushing

2338. 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. 1.34 Wi

C. Wi

D. 0.5 Wi

2339. In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the__________________?
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A. Filtration time only

B. Square root of the velocity

C. Square of the viscosity

D. Washing time only

2340. Percentage saturation is _______________ the relative saturation?
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A. Always greater than

B. None of these

C. Not related to

D. Always smaller than
2341. Toothed roll crushers achieve size reduction by___________________?
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A. Tearing (shear) and compression

B. Impact and attrition

C. Both A. & B.

D. Neither A. nor B.

2342. Energy consumed for crushing one ton of material ranges from ______________ kWh?
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A. 4 to 5

B. 0.01 to 0.1

C. 2 to 3.5

D. 0.5 to 1.5
2343. As per Taggarts formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms) ?
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A. ?(LS)

B. LS

C. 250 LS

D. 93 LS
2344. Which of the following is not used as a surface active agent in a flocculation operation ?
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A. Lime

B. Quartz

C. Sodium silicate

D. Alumina

2345. Moore filter is a ______________ filter ?
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A. Sand

B. Leaf

C. Rotary

D. Press

2346. A propeller agitator_______________?
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A. Runs at very slow speed (2 rpm)

B. All A., B. and C.

C. Is used for mixing high viscosity pastes

D. Produces mainly axial flow
2347. In filtration, the use of filter aid helps in__________________?
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A. Enhancing the cake porosity in case of a dense impermeable cake

B. Accelerating the rate of filtration

C. Deplugging the filter medium

D. Reducing the filtration pressure

2348. 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. ?/?2

B. P. gc/n2. D2. ?

C. P. gc/n3. D2. ?

D. n3. D3. ?/P. gc

2349. Wheat is ground into flour in a___________________?
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A. Fluid energy mill

B. Hammer crusher

C. Roller crusher

D. Impact mill

2350. The assumption made in Elis method in distillation is that enthalpy concentration lines of vapor and liquid are __________________?
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A. Parallel

B. Straight

C. Both parallel and straight

D. Neither parallel nor straight