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chemical engineering mechanical operations MCQs

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 Review each marked answer and report any item that may be outdated or unclear.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
1. Angle of nip of the crushing rolls does not depend upon the_______________?
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A. Product size

B. Feed size

C. Speed of the rolls

D. Diameter of the rolls

2. Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines ?
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A. Pebble mill

B. Rod mill

C. Tube mill

D. Compartment mill

3. Flow of filtrate through the cake in a plate and frame filter press is best described by the ______________ equation?
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A. Fannings

B. Hagen-Poiseuilles

C. Kremser

D. Kozeny-Carman
4. Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively ?
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A. 500C and 50 atm

B. 1000C and 10 atm

C. 200C and 5 atm

D. 1000C and 500 atm

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

B. Screw conveyor

C. Bucket elevator

D. Apron conveyor

6. 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. 1/?2

C. ??

D. 1/?

7. 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. Secondary

B. Primary

C. Fine

D. Ultrafine

8. Which of the following is not used as filter aid ?
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A. Diatomaceous earth

B. Asbestos

C. Rice husk

D. Purified wood cellulose

9. Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids (> 50000 centipoise) ?
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A. Flat blade turbine

B. Helical screw

C. Curved blade turbine

D. Propeller

10. Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is ______________ microns?
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A. 10 to 25

B. < 74

C. < 5

D. > 1000

11. 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. Flocculation

D. Sizing
12. Sphericity of raschig ring (whose length and diameter are equal) is___________________?
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A. < 1

B. 2

C. 1

D. > 1

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

B. Suspended batch basket

C. Disc-bowl

D. Perforated horizontal basket continuous
14. 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. 0.5 to 1.5

D. 2 to 3.5

15. 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__________________?
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A. All A., B. and C.

B. British standard screens

C. German standard screens (DIN 1171) etc

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

16. Which of the following gives the crushing energy required to create new surface ?
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A. Rittingers Law

B. None of these

C. Taggarts rule

D. Ficks law

17. The specific surface of spherical particles is proportional to (where, Dp = diameter of particle)?
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A. 1/D2p

B. 1/Dp

C. D2

D. Dp

18. 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. Vacuum

C. Sand

D. Rotary

19. Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter) ?
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A. 2 D

B. D

C. 0.5 D

D. 1.5 D

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

B. Same throughout the thickness of cake

C. Maximum at the filter medium

D. Minimum at the upstream face