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) ?

Related Mcqs:

1. 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

2. Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity ?

   A. Sphere
   B. Cube
   C. Cylinder (L/D = 1)
   D. Raschig rings

3. The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle) ?

   A. 6/D.ρ
   B. 2/D.ρ
   C. 4/D.ρ
   D. 12/D.ρ

4. In a grinding operation, the limiting particle size is the size of the _______________ particle in the sample?

   A. Smallest
   B. Largest
   C. Either A. or B.
   D. Neither A. nor B.

5. Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πND 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

6. 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.V.ρ
   C. 3.6 A.S. ρ
   D. 3.6 AVS/ρ
   Answer: Option

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. Which of the following relationships between co-efficient 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

9. Energy requirement (per unit mass of material crushed/ground) is highest for__________________?

   A. Jaw crusher
   B. Rod mill
   C. Ball mill
   D. Fluid energy mill

10. The specific surface of spherical particles is proportional to (where, Dp = diameter of particle)?

    A. D2
    B. Dp
    C. 1/Dp
    D. 1/D2p