MCQOPTIONS
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MCQOPTIONS
This section includes 30 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. |
Which of the following relationships between co-efficinet of friction (%u03BC) 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 α |
| D. | μ > tan 2α |
| Answer» B. μ > tan α | |
| 2. |
Which of the following mineral dressing operations is termed as \'comminution\'? |
| A. | Spiralling |
| B. | Panning |
| C. | None of these |
| D. | Tabling |
| Answer» D. Tabling | |
| 3. |
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. | 9.0 kWh/ton |
| B. | 6.35 kWh/ton |
| C. | 25.4 kWh/ton |
| D. | 18 kWh/ton |
| Answer» E. | |
| 4. |
What is the reduction ratio in a fine crushing operation having following feed and product sizes? |
| A. | 0.5 |
| B. | 2 |
| C. | 5 |
| D. | 10 |
| Answer» C. 5 | |
| 5. |
Filtrate flow rate in case of a rotary drum vacuum filter (in which R m < < R c ) is proportional to __________ and the cycle time (where, ? = filtrate viscosity R m = filter medium resistance R c = cake resistance ). |
| A. | ? |
| B. | 1/ ? |
| C. | 1/? |
| D. | 1/? 2 |
| Answer» C. 1/? | |
| 6. |
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 ? = density of material to be crushed, kg/m 3 here, V =? N.D where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m) |
| A. | 3.6 V . W . Dr .? |
| B. | 3.6 V . W . ? |
| C. | 3.6 W . Dr .? |
| D. | 3.6 V . W . Dr /? |
| Answer» B. 3.6 V . W . ? | |
| 7. |
In ball mill operation, the feed size ( D f in meters) and the ball diameter ( D b in metres) are related as ( where, K = grindability constant (varying from 0.9 to 1.4 in increasing order of hard ness)) |
| A. | D b 2 = K . D f |
| B. | D b = K . D f |
| C. | D b 3 = K . D f |
| D. | D b 2 = K . D f 2 |
| Answer» B. D b = K . D f | |
| 8. |
A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 ?m/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is |
| A. | 0.90 ?m/s |
| B. | 1 ?m/s |
| C. | 22.1 ?m/s |
| D. | 0.02 ?m/s |
| Answer» C. 22.1 ?m/s | |
| 9. |
For a turbine agitated and baffled tank, operating at low Reynold's number (based on impeller diameter), the power number ( N p ) varies with N Re as |
| A. | N p ? N Re |
| B. | N p ? N Re |
| C. | N p ? constant |
| D. | N p ? 1/ N Re |
| Answer» E. | |
| 10. |
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 ? = bulk density of material, kg/m 3 ) |
| A. | 3.6 W . D . V .? |
| B. | 3.6 W . D . V . |
| C. | 3.6 W . V .? |
| D. | 3.6 D . V .? |
| Answer» B. 3.6 W . D . V . | |
| 11. |
Vibrating screens have capacity in the range of __________ tons/ft 2 .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 | |
| 12. |
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. | Weber |
| B. | Peclet |
| C. | Brinkman |
| D. | Schmidt |
| Answer» C. Brinkman | |
| 13. |
Mass flow of granular solid ( M ) through a circular opening of dia, D follows |
| A. | M ? D |
| B. | M ? D 2 |
| C. | M ? D 3 |
| D. | M ? D |
| Answer» D. M ? D | |
| 14. |
__________ mean diameter of particles is given by |
| A. | Mass |
| B. | volume |
| C. | Arithmetic |
| D. | Volume surface |
| Answer» C. Arithmetic | |
| 15. |
The basic filtration equation is given as where, V is volume of the filtrate ; A is the filtration area, a is specific cake resistance, ? 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 m 3 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 3 of filtrate to be produced ? Neglect filter medium resistance, Rm ; assume incompressible cake. |
| A. | 10 |
| B. | 20 |
| C. | 25 |
| D. | 30 |
| Answer» C. 25 | |
| 16. |
The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m 2 V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.? = density of solids, kg/m 3 ) |
| A. | 3.6 AVS.? |
| B. | 3.6 A.V.? |
| C. | 3.6 A.S. ? |
| D. | 3.6 AVS/? |
| Answer» B. 3.6 A.V.? | |
| 17. |
The specific surface of sherical particles is proportional to (where, D p = diameter of particle). |
| A. | D 2 p |
| B. | D p |
| C. | 1/ D p |
| D. | 1/ D 2 p |
| Answer» D. 1/ D 2 p | |
| 18. |
A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ? L ) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ? and no cake is formed. The initial pressure drop during filtration is |
| A. | w 2 . R 2 . ? L |
| B. | w 2 . ? 2 . ? L |
| C. | w 2 . ?? L (2 R + ?) |
| D. | w 2 . R . ? L ( R + 2?) |
| Answer» D. w 2 . R . ? L ( R + 2?) | |
| 19. |
Filtration rate through a filter cake is proportional to (where, S = filtering surface R = specific cake resistance ? = viscosity of the filtrate) |
| A. | S |
| B. | 1/ R |
| C. | 1/? |
| D. | all (a), (b) & (c) |
| Answer» E. | |
| 20. |
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 i , then the same for open circuit grinding will be |
| A. | 0.5 W i |
| B. | W i |
| C. | 1.34 W i |
| D. | 3.34 W i |
| Answer» D. 3.34 W i | |
| 21. |
The reduction ratio for grinders is defined as(where, D f and D p are average diameters of feed and product respectively). |
| A. | D f / D p |
| B. | D p / D f |
| C. | D f - D p |
| D. | none of these |
| Answer» B. D p / D f | |
| 22. |
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. | |
| 23. |
Which of the following equations is Rittinger's crushing law ? (where P = power required by the machine, m = feed rate, k = a constant = volume surface mean diameter of feed & product respectively.) |
| A. | P / m = K / D p |
| B. | P / m = K . ln |
| C. | P / m = K . |
| D. | none of these. |
| Answer» D. none of these. | |
| 24. |
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: P o = ?/? N 3 D 5 : Power number Re = ? N D 2 /?: Reynold's number N is the impeller rotational speed, and D is the impeller diameter. |
| A. | P o ? Re -1.0 |
| B. | P o ? Re 0.0 |
| C. | P o ? Re 0.5 |
| D. | P o ? Re 1.0 |
| Answer» C. P o ? Re 0.5 | |
| 25. |
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 ) p |
| B. | ( S / V ) p |
| C. | ( S / V ) 2 p |
| D. | ( S / V ) f |
| Answer» D. ( S / V ) f | |
| 26. |
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 |
| Answer» B. s / c | |
| 27. |
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 ( N ) is proportional to |
| A. | N ° |
| B. | N 1 |
| C. | N 2 |
| D. | N 3 |
| Answer» D. N 3 | |
| 28. |
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» E. | |
| 29. |
Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, V p = volume of one particle, ?= density of particles) |
| A. | m /? . V p |
| B. | m . ?/ V p |
| C. | m . V p /? |
| D. | V p / m . ? |
| Answer» B. m . ?/ V p | |
| 30. |
If dp is the equivalent diameter of a non-spherical particle, V p its volume and sp its surface area, then its sphericity is ? s is defined by |
| A. | ? s = 6 V p /d p s p |
| B. | ? s = V p /d p s p |
| C. | ? s = 6 d p S p /V p |
| D. | ? s = d p S p /V p |
| Answer» B. ? s = V p /d p s p | |