Multiple Choice Questions and Answers (MCQ) on Chemical Engineering Mechanical Operations
01. In case of a hammer crusher, the
(A) Feed may be highly abrasive (Moh’s scale >5)
(B) Minimum product size is 3 mm
(C) Maximum feed size may be 50 mm
(D) Rotor shaft carrying hammers can be vertical or horizontal
Answer: Option D
02. A gravity decanter is meant for the separation of two __________ density.
(A) Immiscible liquids of different
(B) Miscible liquids of different
(C) Immiscible liquids of same
(D) Miscible liquids of same
Answer: Option A
03. Which of the following is not used as filter aid?
(A) Asbestos
(B) Diatomaceous earth
(C) Purified wood cellulose
(D) Rice husk
Answer: Option D
04. To get a fine talc powder from its granules, the equipment used is
(A) Roller crusher
(B) Ball mill
(C) Jaw crusher
(D) Gyratory crusher
Answer: Option B
05. Which of the following mechanical conveyors does not come under the division ‘carriers’?
(A) Belt conveyor
(B) Bucket elevator
(C) Screw conveyor
(D) Apron conveyor
Answer: Option C
06. As per Taggart’s 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).
(A) LS
(B) 93 LS
(C) 250 LS
(D) √(LS)
Answer: Option B
07. Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.
(A) < 5
(B) 10 to 25
(C) < 74
(D) > 1000
Answer: Option C
08. With increase in the capacity of screens, the screen effectiveness
(A) Remains unchanged
(B) Increases
(C) Decreases
(D) Decreases exponentially
Answer: Option C
09. 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)
(A) 0.5 D
(B) D
(C) 1.5 D
(D) 2 D
Answer: Option B
10. Filtration of water in a paper mill is done by a/an __________ filter.
(A) Open sand
(B) Plate and frame
(C) Vacuum leaf
(D) Sparkler
Answer: Option A
11. Angle of nip of the crushing rolls does not depend upon the
(A) Diameter of the rolls
(B) Speed of the rolls
(C) Product size
(D) Feed size
Answer: Option B
12. Reciprocal of sphericity is termed as the
(A) Specific surface ratio
(B) Shape factor
(C) Sauter diameter
(D) Surface area per unit mass
Answer: Option B
13. Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines?
(A) Compartment mill
(B) Rod mill
(C) Pebble mill
(D) Tube mill
Answer: Option B
14. As particle size is reduced
(A) Screening becomes progressively more difficult
(B) Screening becomes progressively easier
(C) Capacity and effectiveness of the screen is increased
(D) None of these
Answer: Option A
15. Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.
(A) Kozeny-Carman
(B) Hagen-Poiseuille’s
(C) Fanning’s
(D) Kremser
Answer: Option A
16. Which of the following achieves the least reduction ratio for a given feed size?
(A) Jaw crusher
(B) Roll crusher
(C) Cone crusher
(D) Gyratory crusher
Answer: Option B
17. Filtrate flow rate in case of a rotary drum vacuum filter (in which Rm < < Rc) is proportional to __________ and the cycle time (where, μ = filtrate viscosity Rm = filter medium resistance Rc = cake resistance).
(A) √μ
(B) 1/√μ
(C) 1/μ
(D) 1/μ2
Answer: Option B
18. Size measurement of ultrafine particles can be best expressed in terms of
(A) Centimetre
(B) Screen size
(C) Micron
(D) Surface area per unit mass
Answer: Option D
19. Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids (> 50000 centipoise)?
(A) Propeller
(B) Helical screw
(C) Flat blade turbine
(D) Curved blade turbine
Answer: Option B
20. Rittinger number which designates the new surface produced per unit of mechanical energy absorbed by the material being crushed, depends on the
(A) State or manner of application of the crushing force
(B) Ultimate strength of the material
(C) Elastic constant of the material
(D) All (A), (B) and (C)
Answer: Option D
21. The specific surface of spherical particles is proportional to (where, Dp = diameter of particle).
(A) D2p
(B) Dp
(C) 1/Dp
(D) 1/D2p
Answer: Option C
22. During filtration operation, the filtrate encounters the resistance of the
(A) Filter medium
(B) Cake
(C) Channel carrying the slurry to the upstream side of the cake and filtrate away from the filter medium
(D) All (A), (B) and (C)
Answer: Option D
23. Separation of materials of the same density based on their sizes by using then-different rates of flow is called
(A) Sorting
(B) Sizing
(C) Flocculation
(D) Elutriation
Answer: Option B
24. __________ is the most suitable for compounding rubber and plastic solids.
(A) Banbury mixer
(B) Pan mixer
(C) Pug mill
(D) Charge can mixer
Answer: Option A
25. Pick out the wrong statement:
(A) Magnetic separation method can be employed to treat both dry & wet ores
(B) Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size
(C) Gyratory crusher is used for coarse crushing
(D) Screens are of stationary, moving and vibratory types
Answer: Option B