Two particles are called to be equal settling, if they are having the same ?

Related Mcqs:

1. A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is_____________?

   A. 0.1
   B. 0.4
   C. 0.6
   D. None of these

2. 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

3. In classification, particles are said to be equal settling, if they have the same terminal velocities in the_______________?

   A. Different fluids
   B. Same fluid
   C. Same field of force
   D. Both B. and C.

4. 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 . ρ/Vp
   C. m . Vp/ρ
   D. Vp/m . ρ

5. Sorting classifiers employing differential settling methods for separation of particles make use of the differences in their_________________?

   A. Particle sizes
   B. Densities
   C. Terminal velocities
   D. None of these

6. ______________ are used for the separation of coarse particles from a slurry of fine particles?

   A. Thickeners
   B. Classifiers
   C. Hydrocyclones
   D. Decanters

7. 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. 6.35 kWh/ton
   B. 9.0 kWh/ton
   C. 18 kWh/ton
   D. 25.4 kWh/ton

8. Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is ______________ microns?

   A. < 5
   B. 10 to 25
   C. < 74
   D. > 1000

9. Gravity settling process is not involved in the working of a________________?

   A. Hydrocyclone
   B. Classifier
   C. Dorr-thickener
   D. Sedimentation tank

10. Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are________________?

    A. Carbonates
    B. Sulphates
    C. Silicates & phosphates
    D. Bi-carbonates