chemical engineering Mcqs
2351. Critical speed of rotation, N (in rps rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec2 and, r = radius of trammel, metre.) ?
comments icon0

A. 2?. ?(g/r)

B. (1/?). ?(g/r)

C. (1/2?). ?(g/r)

D. ?(g/r)

2352. In an interphase mass transfer process, the lesser the solubility of a given solute in a liquid, the higher are the chances that the transfer process will be_________________?
comments icon0
A. Gas phase resistance controlled

B. Driven by a non-linear driving force

C. Liquid phase resistance-controlled

D. Impossible

2353. Sphericity of raschig ring (whose length and diameter are equal) is___________________?
comments icon0

A. > 1

B. 2

C. 1

D. < 1

2354. During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration___________________?
comments icon0

A. At time zero

B. At the end of filtration, but decreases with time subsequently

C. When half the filtrate has been obtained

D. At the end of filtration
2355. Which of the following oxides is not present in hematite iron ore ?
comments icon0

A. Calcium oxide

B. Titanium oxide

C. Cobalt oxide

D. Manganese oxide

2356. The Knudsen diffusivity is dependent on the ______________________?
comments icon0

A. Molecular velocity only

B. Molecular mean free path only

C. Molecular velocity and pore radius of the catalyst

D. Pore radius of the catalyst only

2357. In case of grinding in a ball mill__________________?
comments icon0
A. All A., B. and C

B. Its capacity decreases with increasing fineness of the products

C. Wet grinding achieves a finer product size than dry grinding

D. Grinding cost and power requirement increases with increasing fineness of the products

2358. In case of liquid-liquid binary diffusion, diffusivity of one constituent into another is not dependent on the__________________?
comments icon0

A. Concentration

B. None of these

C. Temperature and pressure

D. Nature of the constituents

2359. ______________ mill is not a revolving mill ?
comments icon0
A. Cage

B. Tube

C. Pebble

D. Compartment

2360. In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the _____________ crushing?
comments icon0

A. Primary

B. Secondary

C. Ultrafine

D. Fine

2361. In case of a revolving mill, wet grinding compared to dry grinding__________________?
comments icon0

A. Complicates handling & classification of the product

B. None of these

C. Requires more energy

D. Has less capacity

2362. For absorbers, high pressure drop results in___________________?
comments icon0

A. Increased efficiency

B. High operating cost

C. Better gas liquid contact

D. Decreased efficiency

2363. Tabling process used for separating two materials of different densities by passing the dilute pulp over a table/deck, which is inclined from the horizontal surface at an angle of about________________?
comments icon0

A. 5 to 10

B. 2 to 5

C. 10 to 15

D. 1 to 2

2364. Reciprocal of sphericity is termed as the________________?
comments icon0
A. Shape factor

B. Specific surface ratio

C. Sauter diameter

D. Surface area per unit mass

2365. A filter press is___________________?
comments icon0

A. Not suitable, if the liquid is the main product

B. Having prohibitively high maintenance cost

C. A batch filter

D. Not suitable for wide range of materials under varying operating conditions of cake thickness

E. pressure

2366. The controlling resistance in a rotary drum vacuum filter is the ________________ resistance?
comments icon0
A. Cake

B. Filter medium

C. Piping

D. None of these

2367. For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter) ?
comments icon0

A. None of these

B. ?/6 = (V/D3)

C. AD/V

D. ? = (A/D2)
2368. In coal washeries, three products namely the valuable product (i.e. clean/washed coal), discarded product (i.e. mineral matter) and an additional concentrated product called _____________ is produced?
comments icon0
A. Middling

B. Tailing

C. Concentrate

D. None of these

2369. Pick out the wrong statement ?
comments icon0

A. uction equipments employ

B. versal jaw crushers

C. More commonly used jaw crusher between Dodge jaw crusher and Blake jaw crusher is the

D. Operating principles of Dodge and Blake jaw crushers are combined in the working of

E. Cutting machines mainly employ attrition for size reduction of solids

F. er one

2370. Refractory bricks are usually dried in a ________________ dryer?
comments icon0

A. Tray

B. Tunnel

C. Festoon

D. Conveyor

2371. To get ultrafine particles, the equipment used is a _________________?
comments icon0
A. Fluid energy mill

B. Ball mill

C. Hammer crusher

D. Rod mill

2372. Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for__________________?
comments icon0

A. American standard screens (ASTM and Tyler standard screens)

B. All A., B. and C.

C. German standard screens (DIN 1171) etc

D. British standard screens

2373. The important dimensional group involved in the power requirement calculation in mixing operation is the _____________ number?
comments icon0

A. Reynolds

B. Froude

C. Both A. & B.

D. Neither A. nor B.

2374. The specific surface of spherical particles is proportional to (where, Dp = diameter of particle)?
comments icon0

A. Dp

B. D2

C. 1/Dp

D. 1/D2p

2375. Sticky material can be dried in a ________________ dryer ?
comments icon0
A. Tray

B. Fluidised bed

C. None of these

D. Rotary

2376. Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ? = density of material to be crushed, kg/m3 here, V =?ND where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m) ?
comments icon0
A. 3.6 V.W.Dr.?

B. 3.6 V.W. ?

C. 3.6 W.Dr.?

D. 3.6 V.W.Dr/?

2377. Dry powdery solid materials are transported by a ______________ conveyor?
comments icon0

A. Bucket

B. None of these

C. Screw

D. Belt

2378. Which is a secondary crusher for a hard & tough stone ?
comments icon0
A. Cone crusher

B. Toothed roll crusher

C. Jaw crusher

D. Impact crusher

2379. The binary diffusivity in gases at atmospheric conditions is about ___________________?
comments icon0

A. 10-4 cm2/sec2

B. 10-1 cm2/sec

C. 10-3 sec/cm

D. 10-9 cm/sec

2380. Size measurement of ultrafine particles can be best expressed in terms of___________________?
comments icon0

A. Micron

B. Screen size

C. Centimetre

D. Surface area per unit mass
2381. Which of the following may prove unsuitable for filtering volatile liquids ?
comments icon0

A. Pressure filter

B. Vacuum filter

C. Gravity filter

D. Centrifugal filter

2382. Vacuum is applied in _______________ zone, in case of a general type continuous rotary drum vacuum filter?
comments icon0

A. Drying

B. All A., B. & C.

C. Filtering

D. Washing

2383. Gummy & sticky materials like molasses, sugar etc. are best transported/handled by using a ______________ conveyor?
comments icon0

A. Drag

B. Screw

C. Ribbon

D. Slat

2384. Rittingers crushing law states that_____________________?
comments icon0

A. For a given machine and feed, crushing efficiency is dependent on the size of the feed &

B. Work required to form a particle of any size is proportional to the square of the surface to

C. Work required to form a particle of a particular size is proportional to the square root of the

D. face to volume ratio of the product

E. Work required in crushing is proportional to the new surface created

F. ume ratio of the product

2385. Which of the following is a continuous filter ?
comments icon0

A. Plate and frame filter

B. None of these

C. Shell and leaf filter

D. Cartridge filter

2386. _____________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid ?
comments icon0

A. Bubble point

B. Dew point

C. Dry bulb temperature

D. Wet bulb temperature

2387. Gyratory crushers compared to the reciprocating jaw crushers__________________?
comments icon0
A. Have greater capacity per unit of discharge area

B. Crush intermittently

C. Have less steady power consumption

D. Are less suitable for coarse materials

2388. Critical humidity of a solid salt means the humidity_____________________?
comments icon0

A. Above which it will always become damp

B. Below which it will always stay dry

C. Both A. and B.

D. Above Which it will always become dry and below which it will always stay damp

2389. Physical absorption is__________________?
comments icon0

A. An irreversible phenomenon

B. A reversible phenomenon

C. Accompanied by evolution of heat

D. Both B. and C.
2390. For coarse reduction of hard solids, use ____________________?
comments icon0

A. Attrition

B. Impact

C. Cutting

D. Compression
2391. For contacting a highly soluble gas with a liquid ____________________?
comments icon0
A. Bubble the gas through liquid

B. Either A. or B. would suffice

C. Spray the liquid on gas stream

D. None of these

2392. In a counter-current extractor, as the axial mixing increases, the extraction efficiency______________________?
comments icon0
A. Decreases

B. Remains unchanged

C. Increases

D. Depends on the pressure of the system

2393. _______________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals?
comments icon0

A. Concentration ratio

B. Separation efficiency

C. Selectivity index

D. None of these

2394. Size reduction of ice and gypsum can be accomplished suitably by a _______________ crusher?
comments icon0
A. Toothed roll

B. Blake jaw

C. None of these

D. Gyratory

2395. _____________ mills are termed as impactors?
comments icon0

A. Rolling-compression

B. None of these

C. Cage

D. Hammer
2396. Which of the following size reduction equipments employs mainly attrition for ultrafine grinding ?
comments icon0
A. All A., B. and C.

B. Fluid energy mill

C. Micronizer

D. Jet mills

2397. Bond crushing law_________________?
comments icon0

A. the square root of the volume to surface ratio of the product

B. Calls for relatively less energy for the smaller product particles, than does the Rittinger law

C. States that the work required for the crushing is proportional to the new surface created

D. States that the work required to form particle of any size from very large feed is proportional

E. Is less realistic in estimating the power requirements of commercial crushers

2398. Only small amount of evaporation of water produces large cooling effects because of its___________________?
comments icon0
A. Large latent heat

B. Small latent heat

C. None of these

D. Low viscosity

2399. 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?
comments icon0

A. 1

B. 0.5

C. 1.34

D. 4.34

2400. Width and speed of a conveyor belt depends upon the ______________ of the material?
comments icon0

A. Lump size

B. Bulk density

C. Both A. & B.

D. Neither A. nor B.