Here are 1000 MCQs on Mechanical Operations (chapterwise).
1. Which of the following explains Mechanical Operations correctly?
a) Deals with Science and Technology of particulate matter
b) Deals with Science and Technology of machine operations
c) Deals with Science, Technology of particulate matter and machine operations
d) None of the mentioned
View Answer
Explanation: Mechanical Operations is a multidisciplinary field that includes Materials Science, Environmental Science, Biomedical Science, Aerospace Science, Agricultural Science, Chemistry, Microbiology, and Cell Science, Pharmacy, and Medicine.
2. Which of the following is not a type of Machine Operations?
a) Turning
b) Drilling
c) Milling
d) Grating
View Answer
Explanation: Turning is a machining method in which the workpiece is spun as cutting tools travel across it on a lathe. Drilling uses drill bits to generate cylindrical holes in solid materials; it is one of the most essential machining techniques since the holes created are typically used to aid with assembly. In contrast to turning processes, where the tool does not spin, milling removes material using revolving cutters.
3. Which of the following is a type of Mechanical Operations generally used in industries?
a) Size reduction
b) Clarification
c) Screening
d) All of the mentioned
View Answer
Explanation: Size reduction is the process of reducing the size of larger particles to smaller particles by applying force to them and breaking them into smaller particles. Clarification is a crucial solid-liquid separation process that relies heavily on gravity. Screening is a separation technique that separates larger particles from smaller particles.
4. Which of the following Mixers are used for Cohesive Solids?
a) Disperser
b) Tumbling mixer
c) Ribbon blender
d) Impact wheels
View Answer
Explanation: There are different types of mixing equipment used according to the type of solids are being mixed.
Mixers used for Cohesive Solids:
- Change can mixer
- Kneader
- Disperser
- Masticator
- Mixing rolls
- Muller mixer
- Mixer extruder
- Pugmill
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Mixers used for free-flowing solids are:
- Ribbon blender
- Internal screw mixer
- Tumbling mixer
- Impact wheels
5. Which of the following Size reduction equipment is commonly used in industries?
a) Impact wheels
b) Roller Mill
c) Kneader
d) All of the mentioned
View Answer
Explanation: Size reduction equipment which is common in industries are classified as:
1. For Course Particles
- Jaw crusher
- Crushing rolls
- Gyratory crusher
2. For intermediate size particles
- Hammermill (Impactor)
- Roller Mill
3. For Small Size Particles
- Ball mill
- Tube mill
- Rod mill
4. For ultrafine size crushing
- Fluid energy mill
- Agitated mill
- Colloid mill
5. By mills based on cutting action
- Slicer
- Dicer
- Cutter
6. By mills based on attrition action
- Attrition mill
6. Which of the following works on the principle of compression and impact?
a) Fine crusher
b) Jaw crusher
c) Tramp crusher
d) Gyratory crusher
View Answer
Explanation: The gyratory crusher involves the operation of both compression and impact at the same time, while jaw crusher only applies compression.
7. Which of the following is used for fine crushing?
a) Jaw crusher
b) Camp crusher
c) Stump battery
d) Dodge crusher
View Answer
Explanation: The stamp battery is used extensively used for fine crushing, stamp battery consists of several stamps weighing 500-1000 kg in weight.
8. Which of the following is the capacity Q in tons?
a) 1.20 ND wds
b) 0.0068 ND wds
c) 10 N D
d) 5 ND wds
View Answer
Explanation: If N is the speed of the roll in rpm and D roll diameter in inches and thus Q = 0.068 ND wds, which gives results in tons per hour.
9. Which of the following works on the principle of impact?
a) Gyratory Mill
b) Jaw crusher
c) Ball mill
d) Roll crusher
View Answer
Explanation: The ball mill works on the principle of impact, it consists of the horizontal cylinder lined with steel or high carbon plates.
10. Which of the following is true, when operating speed is less than critical speed?
a) Bold grinding
b) Effective grinding
c) No grinding
d) Best grinding
View Answer
Explanation: The speed at which the centrifuging occurs is called as the critical speed and little or no grinding tales place during this phase.
11. Which of the following resides more energy?
a) Open circuit
b) Closed Circuit
c) By-pass
d) Bi-lateral
View Answer
Explanation: As the material is passed only once through the crusher, the excessive formation of undersize product takes place resulting in more energy consumption.
12. Which of the following is a standard screen?
a) McCabe screen
b) Camp screen
c) Treybal screen
d) Tyler screen
View Answer
Explanation: One of the most common set of screens is the Tyler screens, this is based on the 200 mesh screen with wire 0.021 inch.
13. Which of the following involves vibrations?
a) Hammer mill
b) Ball mill
c) Roll mill
d) Grizzly screen
View Answer
Explanation: Vibrating grizzlies are simply mounted on eccentrics so that entire assembly is given a back and forth movement or a positive circle throw.
14. Which of the following operates at the slowest speed?
a) Gyrating screens
b) Tumbler
c) Oscillating screen
d) Tromells
View Answer
Explanation: These are characterized by low speed i.e. 300 to 400 rpm oscillation in a plane essentially parallel to the screen cloth.
15. Which of the following can be used for separation of pulp?
a) Liquid cyclone
b) Cone classifiers
c) Drag classifier
d) Elutriator
View Answer
Explanation: The cone classifiers are not suitable for pulp having a tendency to build mud banks, it requires more operating attention than mechanical classifiers.
16. Which is best of the following for fine separation?
a) Drag classifier
b) Tumbler mill
c) Dorr classifier
d) Rake classifier
View Answer
Explanation: Separations as fine as up to 325 mesh can be accomplished at reduced tonnage rates, they are generally used for closed circuit grinding.
17. Which of the following agitation methods in a jet mixer is best suited for pH control?
a) Medium agitation
b) Mild agitation
c) Violent agitation
d) Any mode of agitation can be appropriate for pH control
View Answer
Explanation: In a jet, different agitation methods are used for different applications. Mild agitation is usually used for neutralizing action. Violent agitation is used for pigment blending or disinfection. Medium agitation typically takes place for a time of 3 seconds to 3 minutes and is optimum for pH control.
18. Which of the following has the lowest efficiency?
a) Impellor mixer
b) Agitator mixer
c) Tumbling mixer
d) Propeller mixer
View Answer
Explanation: Agitator mixers for powders can take a similar form to paddle mixers for liquids, but their efficiency is low.
19. Which of the following is best for kneading?
a) Agitator
b) Sigma
c) Propeller
d) Impellor
View Answer
Explanation: The common sigma blade is used for general purpose of kneading, it is capable of starting and operating with other solids and liquids.
20. Which of the following filter may prove unsuitable for filtering volatile liquid?
a) Vacuum
b) Centrifugal
c) Gravity
d) Pressure
View Answer
Explanation: Volatile liquid are tend to evaporate in such conditions pressure filter may be best option to use than the vacuum filter.
21. Which of the following conveyors cannot be recommended for transportation of abrasive material?
a) Apron
b) Belt
c) Chain
d) Flight
View Answer
Explanation: Abrasive material are tend to chip and tear during the flight conveying process and thus may prove inefficient for the work.
22. Which of the following mechanical conveyors does not come under the division carriers?
a) Bucket
b) Apron
c) Belt
d) Screw
View Answer
Explanation: The belt, bucket, and apron are used to carry material from one place to another whereas the screw is used to move things.
23. Which of the following impellers is not an example of axial flow impeller?
a) Pitched turbines
b) Ruston
c) Propeller
d) Hydrofoils
View Answer
Explanation: Ruston is a radial flow impeller. The classification of impeller depends on the angle that the blade makes with the plane of impeller rotation.
24. Which of the following combination of the flow pattern can be observed in an open turbine?
a) Axial only
b) Radial only
c) Mixed
d) Radial and axial
View Answer
Explanation: In an open turbine both radial and axial flow can be observed, whereas in propellers only axial type of flow pattern can be observed. And in equipment like shrouded turbines and paddles axial flow pattern can be observed. The presence of both the flow patterns in an open turbine makes it advantageous over other equipment.
25. Which of the following impeller is best suited in mixing operation in lead, rubber and plastics?
a) Flat blade turbine
b) Paddle
c) Propeller – marine
d) Anchor
View Answer
Explanation: In case of lead, rubber and plastics they require high intensity solid scrubbing which is primarily provided by flat blade turbines. These are used for blending when high shear is required.
26. Which of the following type of paddle agitators are most commonly used?
a) Four Bladed
b) Two bladed and four bladed
c) Two Bladed
d) Three Bladed
View Answer
Explanation: Both two bladed and four bladed paddle agitators are most commonly used in the chemical industry as it provides uniformity and homogeneity in agitation operation.
27. Which of the following is/are examples of paddle agitators?
a) Turbine agitator
b) Propeller agitator
c) Grout agitator
d) Hydrostatic agitators
View Answer
Explanation: Some of the examples of paddle agitators are mudwhip agitator, grout agitators, anchor agitators and many others. Grout agitators are used to slowly stir the materials and prevent separation. The agitators are designed with a vertical shaft and feature specially designed blades and baffles to bring out gentle mixing action.
28. Which of the following is the correct unit of velocity gradient?
a) s-1
b) ms-1
c) m
d) m3s-1
View Answer
Explanation: ms-1 is the unit of velocity, which can be defined as the rate of change of position. ‘m3s-1’ is the unit of throughput, or simply rate of change of volume. ‘m’ is the unit of distance, the route taken by an object. It is also the unit of displacement, the shortest route taken by an object.
29. Which of the following is not a unit of power?
a) kgm2s-3
b) Joule
c) erg/second
d) Horsepower
View Answer
Explanation: erg/second is the unit of power in the CGS system of units. kgm2s-3 which can also be written as Watts, is the unit of power in the SI system of units. Horsepower is the unit of power which is used usually in reference to output of engines. However, Joule is the unit of work.
30. Which of the following gives the total volume of the particles?
a) Mv/Pp
b) Mv/Dp
c) Dp/ Pp
d) m/Pp
View Answer
Explanation: The total volume of the particles is given by m/Pp, where m is the total mass of the sample and Dp is the diameter of the particle.
31. Which of the following works principle of compression?
a) Rod mill
b) Knife cutter
c) Blake jaw crusher
d) Gyratory Crusher
View Answer
Explanation: The jaw crusher works on the principle of the compression, it consists of a pair of jaw between which the feed is crushed.
32. Which of the following is the correct unit of throughput?
a) Square feet per second
b) Meter square
c) Meter cube
d) Cubic feet per minute
View Answer
Explanation: Throughput is a measure of the capacity of the conveyor to handle bulky materials. Throughput is always measured as the rate of volume flow, which implies that the units are of the form, volume per time. Therefore, from the given set of options, cubic feet per minute is the right option as it has the units of volume per time.
33. Which of the following is a modified fluidized bed dryer?
a) Batch fluidized bed dryers
b) Hybrid fluidized bed dryer
c) Semi-continuous fluidized bed dryer
d) Plug flow fluidized bed dryer
View Answer
Explanation: Modified fluidized bed dryers are built to overcome the problems that are faced by conventional fluidized bed dryers. These modified fluidized bed dryers are used in several industrial processes. Recent fluidized bed dryers also implement heat pumps.
34. Which of the following characteristic part of a fluidized system is not needed in every system designed?
a) A gas distributor
b) Heating and cooling coils
c) Plenum
d) Particle bed region
View Answer
Explanation: Heating and cooling coils are preferably required when fluidized beds are associated with heat, i.e.: either an exothermic or an endothermic reaction takes place. These coils are not required in case a major temperature change does not take place.
35. Which of the following is the principle of mixing?
a) Centrifugal force
b) Perpendicular force
c) Shear force
d) Gravitational force
View Answer
Explanation: The principle force of mixing is shear force. The shear force is provided by the movement of the blades and high shear rates can break lumps. These are unaligned forces that push one part of the body in one direction, and the other part in opposite direction.
36. Which of the following is not an example of axial flow impellers?
a) Hydrofoil
b) Low-level mixing impeller
c) Propeller
d) Pitched blade
View Answer
Explanation: Propellers are axial flow impellers that are used in small and portable mixers. Pitched blades are also axial flow impellers that are used when a balance between flow and shear is required. The hydrofoil is an axial flow impeller used when low turbulence is required.
Chapterwise Multiple Choice Questions on Mechanical Operations
1. Mechanical Operations MCQ on Size Reduction
The section contains Mechanical Operations multiple choice questions and answers on solid properties, particle sizes, size reduction and its mechanism, energy utilization, crushing efficiency, size reduction energy and equipment’s, crushers, intermediate and fine crushers, ball mill and its advantages, tumbling mill action, ultra fine grinders, colloid mill, cutting machines, equipment and crushers operations, open and closed circuit grinding and operations.
2. Mechanical Operations Multiple Choice Questions on Mechanical Separation
The section contains Mechanical Operations questions and answers on mechanical separation basics, solid separation by screening, screens, screening equipment’s, solid particles classification, magnetic separation, electrostatic separator, floatation, sedimentation, thickeners and cyclone separators.
3. Mechanical Operations MCQ on Filtration
The section contains Mechanical Operations MCQs on filtration basics and theory, relation between cake thickness and filtrate, liquid flow through cloth, filtrate flow through cake and cloth, compressible filter cakes, pressure filters, optimum time cycle, filter press advantages, leaf and rotary filters, horizontal belt and prayon continuous filters, construction materials, equipment’s, critical speed and centrifuge filtration.
4. Mechanical Operations Multiple Choice Questions on Mixing
The section contains Mechanical Operations multiple choice questions and answers on mixing basics and equipment, impellers properties, propeller, open and shrouded turbine, paddle, draft tubes, flow, power, entrainment, flow patterns, interpretation, baffles, velocity patterns and gradient, jet and static mixers, impeller location, mixer extruders, turbine design, power requirements, solids and dry powder mixing, blending granular solids and rate of mixing.
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5. Mechanical Operations MCQ on Fluid-Solid System
The section contains Mechanical Operations questions and answers on fluidization and its types, fluidized system characteristics, solids flow through particle, bubbles and drops settling, fluidization velocity, spherical particles, fluidisation applications and hindered setting.
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6. Mechanical Operations Multiple Choice Questions on Handling of Solids
The section contains Mechanical Operations MCQs on bulk solid nature, conveyors, belt conveyors and its design, belt construction, handling solid basics, chain and flight conveyors, belt speed selection, drag and flight conveyors construction, en-masse and screw conveyors, pneumatic conveyors and its design.
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Wish you the best in your endeavor to learn and master Mechanical Operations!