MCQOPTIONS
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MCQOPTIONS
This section includes 552 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Power required to drive a ball mill with a particular ball load is proportional to (where, = diameter of ball mill ) |
| A. | 1/ |
| B. | 1/ |
| Answer» D. | |
| 2. |
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 μrn is |
| A. | 6.35 kWh/ton |
| B. | 9.0 kWh/ton |
| C. | 18 kWh/ton |
| D. | 25.4 kWh/ton |
| Answer» D. 25.4 kWh/ton | |
| 3. |
Which of the following relationships between co-efficinet of friction (μ) between rock & roll and a (half of the angle of nip) of the particle to be crushed is correct ? |
| A. | μ > tan α |
| B. | μ ≥ tan α |
| C. | μ > tan 2α |
| D. | μ ≤ tan α |
| Answer» C. μ > tan 2α | |
| 4. |
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, = impeller diameter) |
| A. | 0.5 |
| B. | 1.5 |
| C. | 2 |
| Answer» C. 2 | |
| 5. |
Filtration rate through a filter cake is proportional to (where, = filtering surface = specific cake resistance μ = viscosity of the filtrate) |
| A. | 1/ |
| B. | 1/μ |
| C. | all (a), (b) & (c) |
| Answer» E. | |
| 6. |
The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is W, then the same for open circuit grinding will be |
| A. | 0.5 W |
| B. | W |
| C. | 1.34 W |
| D. | 3.34 W |
| Answer» D. 3.34 W | |
| 7. |
The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake) |
| A. | ∝ ΔP |
| B. | ∝ 1/ ΔP |
| C. | ∝ |
| D. | independent of ΔP |
| Answer» E. | |
| 8. |
rpm of a trommel at critical speed is given by (where, = Diameter of trommel in ft) |
| A. | 76.75 |
| Answer» C. | |
| 9. |
At low Reynold's number, the power () required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: = ρ/ρ : Power number Re = ρ /μ: Reynold's number is the impeller rotational speed, and is the impeller diameter. |
| A. | ∝ Re |
| B. | ∝ Re |
| C. | ∝ Re |
| D. | ∝ Re |
| Answer» C. ∝ Re | |
| 10. |
The critical speed of a trommel () is related to its dia () as |
| A. | N ∝ |
| B. | N ∝ |
| C. | N ∝ D |
| D. | N ∝ |
| Answer» B. N ∝ | |
| 11. |
As per Taggart's formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, = Length of feed opening, cms = Maximum width of discharge opening, cms ) |
| A. | 93 |
| B. | 250 |
| Answer» C. | |
| 12. |
The specific surface of sherical particles is proportional to (where, = diameter of particle). |
| A. | 1/ |
| B. | 1/ |
| Answer» D. | |
| 13. |
Reciprocating screens are normally inclined at an angle of 5° with the horizontal and employ gyratory motion at feed end & reciprocating motion at the discharge end. They are not suitable for the screening of the |
| A. | light metal powder down upto 4 meshsize. |
| B. | dry chemicals. |
| C. | heavy tonnages of rocks or gravel. |
| D. | powdered food & granular materials. |
| Answer» D. powdered food & granular materials. | |
| 14. |
The reduction ratio for grinders is defined as(where, and are average diameters of feed and product respectively). |
| A. | / |
| B. | / |
| C. | - |
| D. | none of these |
| Answer» B. / | |
| 15. |
Mass flow of granular solid () through a circular opening of dia, follows |
| A. | ∝ |
| B. | ∝ |
| C. | ∝ |
| D. | ∝ |
| Answer» D. ∝ | |
| 16. |
In a mixer, the quantity, (. /) is termed as __________ number(where, = longitudinal velocity of material, = length of the mixer, = diffusivity in axial mixing). |
| A. | Weber |
| B. | Peclet |
| C. | Brinkman |
| D. | Schmidt |
| Answer» C. Brinkman | |
| 17. |
Feed size of ≥ 25 cms can be accepted by |
| A. | ball mill |
| B. | rod mill |
| C. | fluid energy mill |
| D. | jaw crusher |
| Answer» E. | |
| 18. |
The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed () is proportional to |
| A. | ° |
| Answer» D. | |
| 19. |
The basic filtration equation is given as where, is volume of the filtrate ; is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and is the concentration of the solids in the feed slurry. In a 20 minutes constant rate filtration, 5 m 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 m of filtrate to be produced ? Neglect filter medium resistance, ; assume incompressible cake. |
| A. | 10 |
| B. | 20 |
| C. | 25 |
| D. | 30 |
| Answer» C. 25 | |
| 20. |
The resistance offered by the filter used in a bag filter is proportional to (where, = dust concentration, and = particle size ) |
| A. | / |
| B. | / |
| C. | . |
| D. | 1/ |
| E. | . |
| Answer» B. / | |
| 21. |
Vibrating screens have capacity in the range of __________ tons/ft .mm mesh size. |
| A. | 0.2 to 0.8 |
| B. | 5 to 25 |
| C. | 50 to 100 |
| D. | 100 to 250 |
| Answer» B. 5 to 25 | |
| 22. |
The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.ρ = density of solids, kg/m) |
| A. | 3.6 AVS.ρ |
| B. | 3.6 A.V.ρ |
| C. | 3.6 A.S. ρ |
| D. | 3.6 AVS/ρ |
| Answer» B. 3.6 A.V.ρ | |
| 23. |
Kick's law relates to |
| A. | energy consumption |
| B. | final particle size |
| C. | feed size |
| D. | none of these |
| Answer» B. final particle size | |
| 24. |
General crushing equation is given by . Bond's crushing law isobtained by solving this equation for n = __________ and feed of infinite size. |
| A. | 1 |
| B. | 1.5 |
| C. | 2 |
| D. | 2.5 |
| Answer» C. 2 | |
| 25. |
Filtrate flow rate in case of a rotary drum vacuum filter (in which < < ) is proportional to __________ and the cycle time (where, μ = filtrate viscosity = filter medium resistance = cake resistance ). |
| A. | 1/ |
| B. | 1/μ |
| C. | 1/μ |
| Answer» C. 1/μ | |
| 26. |
For a turbine agitated and baffled tank, operating at low Reynold's number (based on impeller diameter), the power number () varies with as |
| A. | ∝ |
| B. | ∝ |
| C. | → constant |
| D. | ∝ 1/ |
| Answer» E. | |
| 27. |
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. | 0.90 μm/s |
| B. | 1 μm/s |
| C. | 22.1 μm/s |
| D. | 0.02 μm/s |
| Answer» C. 22.1 μm/s | |
| 28. |
Screen capacity is proportional to (where, = screen aperture) |
| A. | 1/ |
| Answer» B. | |
| 29. |
The cummulative mass fraction of particles smaller than size dj for a collection of Ni particles of diameter di and mass mi (i = 1, 2, 3, ...... ∞) is given by |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» C. [C]. | |
| 30. |
The basic filtration equation is given as 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. | 10 |
| B. | 20 |
| C. | 25 |
| D. | 30 |
| Answer» C. 25 | |
| 31. |
Velocity of a small particle of diameter 'Dp' at a distance 'r' from the rotational axis of a cyclone rotating at an angular speed 'ω' is given by (the other symbols are as per standard notation) |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 32. |
The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m2 V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.ρ = density of solids, kg/m3) |
| A. | 3.6 AVS.ρ |
| B. | 3.6 A.V.ρ |
| C. | 3.6 A.S. ρ |
| D. | 3.6 AVS/ρ |
| Answer» B. 3.6 A.V.ρ | |
| 33. |
Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripherial velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πN.D where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m) |
| A. | 3.6 V.W.Dr.ρ |
| B. | 3.6 V.W. ρ |
| C. | 3.6 W.Dr.ρ |
| D. | 3.6 V.W.Dr/ρ |
| Answer» B. 3.6 V.W. ρ | |
| 34. |
Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ρ = bulk density of material, kg/m3) |
| A. | 3.6 W.D.V.ρ |
| B. | 3.6 W.D.V. |
| C. | 3.6 W.V.ρ |
| D. | 3.6 D.V.ρ |
| Answer» B. 3.6 W.D.V. | |
| 35. |
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. ) |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» B. [B]. | |
| 36. |
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. | s = 6 Vp/dp sp |
| B. | s = Vp/dp sp |
| C. | s = 6 dp Sp/Vp |
| D. | s = dp Sp/Vp |
| Answer» B. s = Vp/dp sp | |
| 37. |
Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed? |
| A. | et grinding in low viscous suspension |
| B. | et grinding in high viscous suspension |
| C. | ry grinding of large particles (upto 1.25 cms) |
| D. | ry grindng of large particles in un-baffed mills |
| Answer» E. | |
| 38. |
Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation? |
| A. | heck plates |
| B. | aw plates |
| C. | oggles |
| D. | rush shaft |
| Answer» C. oggles | |
| 39. |
At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5 : Power number Re = ρ N D2/μ: Reynold's number N is the impeller rotational speed, and D is the impeller diameter. |
| A. | o ∝ Re-1.0 |
| B. | o ∝ Re0.0 |
| C. | o ∝ Re0.5 |
| D. | o ∝ Re1.0 |
| Answer» C. o ∝ Re0.5 | |
| 40. |
Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids ( > 50000 centipoise)? |
| A. | ropeller |
| B. | elical screw |
| C. | lat blade turbine |
| D. | urved blade turbine |
| Answer» C. lat blade turbine | |
| 41. |
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. | /ρ . Vp |
| B. | . ρ/Vp |
| C. | . Vp/ρ |
| D. | p/m . ρ |
| Answer» B. . ρ/Vp | |
| 42. |
Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher? |
| A. | od mill |
| B. | luid energy mill |
| C. | yratory crusher |
| D. | all mill |
| Answer» D. all mill | |
| 43. |
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration? |
| A. | arabola |
| B. | traight line |
| C. | yperbola |
| D. | xponential curve |
| Answer» B. traight line | |
| 44. |
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. | 0.5 |
| B. | 0 |
| C. | 0.76 |
| D. | 0.66 |
| Answer» E. | |
| 45. |
For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid? |
| A. | ozney-Karman equation |
| B. | eva |
| C. | lake-Plummer equation |
| D. | one of these |
| Answer» B. eva | |
| 46. |
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. | ucket conveyor |
| B. | light conveyor |
| C. | crew conveyor |
| D. | oth B and C |
| Answer» E. | |
| 47. |
What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls? |
| A. | 6° |
| B. | 2° |
| C. | 0° |
| D. | 6° |
| Answer» C. 0° | |
| 48. |
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. | ompartment mill |
| B. | od mill |
| C. | ebble mill |
| D. | ube mill |
| Answer» C. ebble mill | |
| 49. |
The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is Wᵢ, then the same for open circuit grinding will be |
| A. | 0.5 Wᵢ |
| B. | Wᵢ |
| C. | 1.34 Wᵢ |
| D. | 3.34 Wᵢ |
| Answer» D. 3.34 Wᵢ | |
| 50. |
__________ mills fall in the category of tumbling mills. |
| A. | Ball and pebble |
| B. | Rod and tube |
| C. | Compartment |
| D. | all (a), (b) & (c) |
| Answer» E. | |