New Chemical Engineering MCQs – Competitive Mechanical Operations MCQs
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Latest Chemical Engineering MCQs
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Latest Mechanical Operations Mcqs
The most occurred mcqs of Mechanical Operations in past papers. Past papers of Mechanical Operations Mcqs. Past papers of Mechanical Operations Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Mechanical Operations Mcqs. The Important series of Mechanical Operations Mcqs are given below:
Balls for ball mills are never made of_________________?
A. Cast iron
B. Lead
C. Forged/cast steel
D. Alloy steel
In froth floatation, chemical agent added to cause air adherence is called___________________?
A. Collector
B. Modifier
C. Frother
D. Activator
In a roll crusher, both the rolls_________________?
A. Are rotated towards each other
B. Have the same diameter
C. Run either at the same or different speeds
D. All A., B. and C.
In a mixer, the quantity, (v. L/D) is termed as __________ number (where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing) ?
A. Brinkman
B. Peclet
C. Weber
D. Schmidt
A pebble mill_________________?
A. Is a ball mill
B. Is a tube mill lined with ceramic or other non-metallic liner
C. Employs flints or ceramic pebbles as the grinding medium
D. Both B. and C.
Mass flow of granular solid (M) through a circular opening of dia, D follows_____________________?
A. M ∝ D2
B. M ∝ √D
C. M ∝ D3
D. M ∝ D
Size reduction does not occur due to compression in case of________________?
A. Rod mills
B. Jaw crushers
C. Gyratory crushers
D. Smooth roll crushers
The capacity of a belt conveyor depends upon two factors. If one is the cross-section of the load, the other is the _____________ of the belt?
A. Speed
B. Length
C. Thickness
D. None of these
The grinding in a hammer crusher takes place due to the_______________?
A. Impact
B. Attrition
C. Both A. & B.
D. Neither A. nor B.
Which of the following is not an ultrafine grinder (colloid mill) ?
A. Agitated mills and fluid energy mills
B. Micronizers
C. Toothed roll crusher
D. Hammer mills with internal classification
Compressibility co-efficient for an absolutely compressible cake is_______________?
A. ∞
B. 1
C. 0 to 1
D. 0
If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by________________?
A. φs = 6 Vp/dpsp
B. φs = 6 dpSp/Vp
C. φs = Vp/dpsp
D. φs = dpSp/Vp
A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 μm/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is_________________?
A. 22.1 μm/s
B. 1 μm/s
C. 0.90 μm/s
D. 0.02 μm/s
Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher ?
A. Fluid energy mill
B. Rod mill
C. Gyratory crusher
D. Ball mill
Petroleum Refinery Engineering Mcqs
Handling of ashes and similar materials can be done best by a ______________ conveyor?
A. Belt
B. Drag or slat
C. Flight
D. Ribbon
Size reduction of the ______________ can be suitably done by ball mills, crushing rolls and rod mills?
A. Metalliferous ores
B. Basic slags
C. Non-metallic ores
D. Asbestos & mica
For spheres, the specific surface shape factor is given by___________________?
A. AD/V
B. A/V
C. D/V
D. √(AD/V)
A _____________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end?
A. Compartment
B. Rod
C. Tube
D. Pebble
Cake resistance is___________________?
A. Independent of pressure drop
B. Decreased with the time of filtration
C. Important in the beginning of filtration
D. None of these
Colloid mills achieve size reduction mainly by___________________?
A. Cutting
B. Attrition
C. Impact
D. Compression
The basic filtration equation is given as dt/dV = (μ/A ΔP). [(α .CV/A) + Rm], where, V is volume of the filtrate; A is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and C is the concentration of the solids in the feed slurry. In a 20 minutes constant rate filtration, 5 m3 of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m3 of filtrate to be produced? Neglect filter medium resistance, Rm; assume incompressible cake ?
A. 25
B. 20
C. 10
D. 30
A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is ___________________?
A. ½w2 . δ2 . ρL
B. ½w2 . R2 . ρL
C. ½w2 . δρL (2R + δ)
D. ½w2 . R . ρL(R + 2δ)
Equivalent diameter of a particle is the diameter of the sphere having the same __________________?
A. Ratio of surface to volume as the actual volume
B. Volume as the particle
C. Ratio of volume to surface as the particle
D. None of these
Which of the following is not accomplished by agitation of liquids in agitators ?
A. Dispersing immiscible liquid in form of emulsion
B. Blending of immiscible liquids
C. Dispersing gas in liquid
D. Suspending solid particles
_____________ is the most commonly used ‘filter aid’?
A. Diatomaceous earth
B. Vermiculite
C. Fuller’s earth
D. Semi-plastic clay
Fuels And Combustion Mcqs
For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a__________________?
A. Buhrstone mill
B. Crushing rolls
C. Ball mill
D. Hammer mill
For the preliminary breaking of hard rock, we use a____________________?
A. Gyratory crusher
B. Tube mill
C. Ball mill
D. Squirrel-cage disintegrator
Jigging is a technique by which different particles can be____________________?
A. Separated by particle size
B. Separated by particle shape
C. Separated by particle density
D. Mixed
_______________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products?
A. Roller
B. Buhrstone
C. Attrition
D. Pebble
The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond’s law) of the energy to grind the particles from a very large size to 50 μm is________________?
A. 9.0 kWh/ton
B. 6.35 kWh/ton
C. 18 kWh/ton
D. 25.4 kWh/ton
What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls ?
A. 1.0
B. 0.5
C. 2.76
D. 0.66
According to Taggart’s rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than_______________?
A. 0.184
B. 0.0184
C. 0.00184
D. 1.84
Wet sieving is employed, when the product contains ________________ materials?
A. Coarse
B. Large quantity of very fine
C. Abrasive
D. Non-sticky
Size reduction mechanism used in Jaw crushers is__________________?
A. Cutting
B. Compression
C. Attrition
D. Impact
Solid particles separation based on the difference in their flow velocities through fluids is termed as the__________________?
A. Elutriation
B. Classification
C. Clarification
D. Sedimentation
The mechanism of size reduction by a hammer mill is by impact and attrition between the________________?
A. Feed particles
B. Grinding element & the housing
C. Both A. and B.
D. Neither A. nor B.
Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of__________________?
A. Stainless steel
B. Bronze
C. Flint or porcelain
D. Concrete
During size reduction by a jaw crusher, the energy consumed decreases with the__________________?
A. Decreasing machine capacity
B. Decreasing size of product at constant size of feed
C. Increasing size of feed at constant reduction ratio
D. None of these
Out of the following size reduction equipments, the maximum feed size can be accepted by the__________________?
A. Ball mill
B. Tube mill
C. Jaw crusher
D. Jet pulveriser
The capacity of a classifier in ‘tons of solid/hr’ is given by (where, A = cross-sectional area in m2, V = rising velocity of fluid in m/sec, S = percentage of solids in the suspension by volume, ρ = density of solids in kg/m3)_________________?
A. 3.6 AVS.ρ
B. 3.6 A.S. ρ
C. 3.6 A.V.ρ
D. 3.6 AVS/ρ
For a turbine agitated and baffled tank, operating at low Reynold’s number (based on impeller diameter), the power number (Np) varies with NRe as_________________?
A. Np ∝ √NRe
B. Np ∝ NRe
C. Np → constant
D. Np ∝ 1/NRe
Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a ______________ conveyor?
A. Slat or drag
B. Flight
C. Ribbon
D. Screw
Screen efficiency is______________________?
A. Recovery
B. Recovery/rejection
C. Rejection
D. None of these
In case of a hammer crusher ?
A. Maximum acceptable feed size is 30 cms
B. Crushing takes place by impact breaking
C. Reduction ratio can be varied by adjusting the distance from cage to hammers
D. All A., B. and C.
Mechanical Operations Mcqs
To remove very small amount of tiny solid impurities from liquid, we use a_____________________?
A. Vacuum filter
B. Pressure filter
C. Centrifugal filter
D. Coagulant
_____________________ baffles are provided in ball mills ?
A. Horizontal
B. Only two
C. No
D. None of these
Crushing efficiency of a machine ranges between __________________ percent?
A. 0.1 to 2
B. 20 to 25
C. 5 to 10
D. 50 to 70
Rod mills employed for grinding_________________?
A. Employ a steel shell having L/D ratio of 1.5 to 3.0
B. Employ steel rods of 2-12 cms diameter extending over full length of the mill
C. Is useful for handling sticky materials
D. All A , B & C
Sauter mean diameter is the same as the ______________ mean diameter?
A. Arithmetic
B. Mass
C. Volume-surface
D. Geometric
Ultrafine grinders operate principally by_________________?
A. Impact
B. Slow compression
C. Attrition
D. Cutting action
Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, Vp = volume of one particle, ρ= density of particles) ?
A. m/ρ . Vp
B. m . Vp/ρ
C. m . ρ/Vp
D. Vp/m . ρ
Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of_____________________?
A. Cams or eccentric shafts
B. Electromagnets
C. Unbalanced flywheels
D. Either A., B. or C.
According to Bond crushing law, the work required to form particle of size ‘D’ from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively) ?
A. (S/V)2p
B. √(S/V)p
C. (S/V)p
D. (S/V)f
Which of the following is the most suitable for handling fibrous and dense slurries ?
A. Turbine agitator
B. Cone type agitator
C. Propeller agitator
D. Radial propeller agitator
A belt conveyor used for the transportation of materials can___________________?
A. Travel at a speed upto 300 metres/minute
B. Run upto 1 km
C. Handle materials upto 5000 tons/hr
D. All A., B. and C.
______________________ balls capable of grinding the feed in a ball mill gives the maximum efficiency ?
A. Maximum size
B. Minimum size
C. Cast iron
D. Elliptical
The maximum slope of a belt conveyor can be_____________________?
A. 45°
B. 30°
C. 15°
D. 60°
The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the__________________?
A. Gravity settling chamber
B. Venturi atomiser
C. Electro-static precipitator
D. Cyclone separator
For separation of sugar solution from settled out mud, we use a ___________________ filter?
A. Plate and frame
B. Sparkler
C. Centrifugal
D. Rotary drum vacuum
Additives used for promoting the flocculation of particles is a/an _____________________?
A. Surface active agent
B. Electrolyte
C. Both A. & B.
D. Neither A. nor B.
Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them ?
A. Jaw crusher, Ball mill, Fluid energy mill
B. Fluid energy mill, Jaw crusher, Ball mill
C. Ball mill, Jaw crusher, Fluid energy mill
D. Fluid energy mill, Ball mill, Jaw crusher
Mechanical conveyors which push the material along an endless trough or tube are called scrappers. Which of the following conveying equipments comes under the category of „scrappers‟ ?
A. Bucket conveyor
B. Screw conveyor
C. Flight conveyor
D. Both B. and C.
Choke crushing (in case of a Jaw crusher) compared to free crushing__________________?
A. Consumes less power
B. Results in increased capacity
C. Consumes more power
D. Both A. and C.
As the product becomes finer, the energy required for grinding___________________?
A. Is same as for coarser grinding
B. Increases
C. Decreases
D. Is 1.5 times that for coarser grinding
To produce talcum powder, use_____________________?
A. Ball mill
B. Jet mill
C. Hammer mill
D. Pin mill
Temperature of the product during ultrafine grinding_____________________?
A. Increases
B. Remain constant
C. Decreases
D. May increase or decrease; depends on the material being ground
The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant ______________ filtration?
A. Pressure
B. Rate
C. Both A. & B.
D. Neither A. nor B.
The resistance offered by the filter used in a bag filter is proportional to (where, c = dust concentration, and s = particle size)?
A. c/s
B. s . c
C. s/c
D. 1/s . c
Limestone is normally crushed in a _____________________?
A. Ball mill
B. Hammer crusher
C. Roll crusher
D. Tube mill
Screen capacity is not a function of__________________?
A. Screening mechanism
B. Its openings size
C. Screening surface
D. Atmospheric humidity