Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Particle Size

1 - Question

What is Φs?
a) Sphere
b) Cubicity
c) Sphericity
d) Void age

Explanation: Φs is defined as the measure of the roundness of a sphere, it is also the ratio of the surface area of same volume particle and the surface area of particle

2 - Question

For a spherical particle of diameter Dp, Φs is ____
a) 0
b) 0.5
c) 1
d) 2

Explanation: As the particle is totally spherical the Sphericity is always 1, for a sphere of diameter Dp, Φs = 1.

3 - Question

For any non-spherical particle, Sphericity is defined as _____
a) 6Vp/DpPs
b) 6Vp/PsSp
c) Vp/DpSp
d) 6Vp/DpSp

Explanation: Sphericity for any non-spherical particle is defined as 6Vp/DpSp, where Dp is the diameter and Vp and Sp are volume and surface area respectively.

4 - Question

For a crushed material, Φs lies between _____
a) 0.6 to 0.8
b) 1 to 2
c) 1.2 to 1.8
d) 1.6 to 1.8

Explanation: As per the empirical calculations and the final results obtained from various experimental values the Φs is calculated to be between 0.6 and 0.8.

5 - Question

For cubes and cylinders, what is Φs?
a) 0.65 and 0.50
b) 0.81 and 0.87
c) 0.660 and 0.556
d) 13.2 and 12.3

Explanation: For cubes and cylinders for which the length L equals to the diameter, equivalent diameter is greater than L, Φs would be 0.81 and 0.87.

6 - Question

Which of the following gives the total volume of the particles?
a) m/Pp
b) Dp/ Pp
c) Mv/Pp
d) Mv/Dp

Explanation: The total volume of the particles is given by m/Pp, where m is the total mass of the sample and Dp is the diameter of the particle.

7 - Question

Which of the following gives the number of particles?
a) mVp/Pp
b) Dp/ Pp
c) m/PpVp
d) Mv/Dp

Explanation: The total number of the particles is given by m/PpVp, where m is the total mass of the sample, Dp is the diameter and Vp is the volume of particle.

8 - Question

Which of the following gives the total surface area of the particle?
a) N*Sp
b) Vp*Sp
c) Sp/Dp
d) Sp/Vp

Explanation: The total surface area of the particle is given by A = N*Sp, where N is the number of the particles and Sp is the surface area of individual particle.

9 - Question

The two basic methods of analysis are ______
a) Cumulative and Affirmative
b) Cumulative and Frequency
c) Frequency and Affirmative
d) Affirmative and Conservative

Explanation: The two basic method of analysis of screening are Cumulative and Frequency plot techniques, one uses particle size while other one uses screen size.

10 - Question

What is NPr?