Mechanical Unit Operations in Chemical Engineering pdf MCQ - Set 04 - ObjectiveBooks

Mechanical Unit Operations in Chemical Engineering pdf MCQ - Set 04

Practice Test: Question Set - 04

1. Filtration capacity of a rotary drum vacuum filter depends upon the
    (A) Cake thickness
    (B) Characteristics of the feed slurry
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

2. 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) Po  Re-1.0
    (B) Po  Re0.0
    (C) Po  Re0.5
    (D) Po  Re1.0

3. Bond crushing law
    (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law
    (B) Is less realistic in estimating the power requirements of commercial crushers
    (C) States that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product
    (D) States that the work required for the crushing is proportional to the new surface created

4. The critical speed of a trommel (N) is related to its dia (D) as
    (A) N  1/√D
    (B) N  √D
    (C) N D
    (D) N  1/D

5. Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle).
    (A) 6.V/D.S
    (B) V/6D.S
    (C) D.S/V
    (D) V/D.S

6. In screen analysis, the notation +5 mm/-10 mm means particles passing through
    (A) 10 mm screen and retained on 5 mm screen
    (B) 5 mm screen and retained on 10 mm screen
    (C) Both 5 mm and 10 mm screens
    (D) Neither 5 mm nor 10 mm screen

7. A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate.
    (A) Compressible cakes and laminar
    (B) Incompressible cake and laminar
    (C) Compressible cake and turbulent
    (D) Incompressible cake and turbulent

8. Cement clinker is reduced to fine size by a
    (A) Roll crusher
    (B) Ball mill
    (C) Tube mill
    (D) Hammer mill

9. Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.
    (A) 1.0
    (B) 0.5
    (C) 1.34
    (D) 4.34

10. Grinding efficiency of a ball mill is of the order of __________ percent.
    (A) 1-5
    (B) 40-50
    (C) 75-80
    (D) 90-95

11. Which of the following is not used as a surface active agent in a flocculation operation?
    (A) Sodium silicate
    (B) Quartz
    (C) Lime
    (D) Alumina

12. Separation of isotopes is generally done using a/an __________ centrifuge.
    (A) Ultra
    (B) Disk-bowl
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

13. For transporting pasty material, one will use a/an
    (A) Apron conveyor
    (B) Belt conveyor
    (C) Screw conveyor
    (D) Bucket elevator

14. Toothed roll crushers achieve size reduction by
    (A) Tearing (shear) and compression
    (B) Impact and attrition
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

15. Dispersion of a gas through liquid is done by using a
    (A) Sparger
    (B) Kneader
    (C) Masticator
    (D) None of these

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