Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Filtration in a Centrifuge

1 - Question

If the settling is carried out with high concentrations of solids to liquid so that particles close together, the condition is called as _______
a) Hindered settling
b) Terminal settling
c) Gross settling
d) Fundamental settling

Explanation: When particle are close together that collision between the particles is continuous and relative fall of particles occur, it is called as hindered settling.

2 - Question

The selection of material handling system depends upon the constituents particles.
a) True
b) False

Explanation: The selection of particles for a certain product depends upon the nature of characteristics of the material.

3 - Question

______ is the percentage of total volume not occupied by the particles.
a) Free space
b) Void age
c) Open volume
d) Gross volume

Explanation: A bulk solid is a combination of particles and space and the percentage of total volume not occupied by the particles is referred as void age.

4 - Question

What does the below equation represent?

a) Void density
b) Bulk density
c) Weight fraction
d) Mole fraction

Explanation: The apparent or bulk density of granular material is defined as the mass of the material divided by its total volume of particles and voids.

5 - Question

______ is defined as the mass of the solids divided by volume occupied by the solids.
a) True density
b) Bulk density
c) Void density
d) Mole fraction

Explanation: True density is defined as the mass of the solids divided by volume occupied by the solid i.e (Mass of solid/Volume) and its unit is Kg/m3.

6 - Question

What does the following represents?
ρba(1- ϵ)
a) Relation of particle a and b
b) Relation of bulk and true densities
c) Relation of two void age
d) Can’t be specified

Explanation: The relation between the apparent and true densities is given by the following relation, where ε is the void age of the particles.

7 - Question

Bulk density of a mixture depends upon ______
a) Weight of particles
b) Density of particles
c) Size of particles
d) Shape of particles

Explanation: Bulk density of a mixture of particles different sizes will depend upon the extent to which particles are able to fit into the space among them.

8 - Question

What are the sizes of a coarse solid?
a) 5 – 100 mm
b) 0.3 – 5 mm
c) 10 -100 micrometer
d) < 1 micrometer

Explanation: The coarse solid are in the range of particle size between 5 to 100 millimeter, whereas fine particles are of range in micrometer, common examples are coal.

9 - Question

What are the sizes of a coarse powder?
a) 5 – 100 mm
b) 0.3 – 5 mm
c) 100 – 300 micrometer
d) 5 to 100 micrometer

Explanation: The best example of a coarse powder is the table salt and the wheat flour that we use, particles at range of 0.3 to 5 mm are granular in nature.

10 - Question

If the angle of repose is said to be 260, then it is ____
a) Very free flowing
b) Free flowing
c) Cohesive
d) Very cohesive