# Mechanical Operations Questions and Answers – Theory of Filtration

This set of Mechanical Operations Multiple Choice Questions & Answers (MCQs) focuses on “Theory of Filtration”.

1. The ratio of void volume and total surface area of particles is defined as _____
a) Resistance
c) Repulsion
d) Void age

Explanation: The hydraulic radius which is defined as the flow area per unit wetted perimeter and is represented by RH.

2. What does the ε represents?
a) Porosity
b) Density
c) Viscosity
d) Acidity

Explanation: The ratio of void volume and the total volume is defined as the porosity, which is denoted by ε.

3. Calculate ε, if the total area is 45 m2 and the void area is 100 m2?
a) 10.5
b) 0.45
c) 2.222
d) 0.89

Explanation: As we know ε = void area/total area = 100/45 = 2.222.

4. Calculate the hydraulic radius, if porosity is 0.6 and specific gravity is 1.50?
a) 1
b) 0.6
c) 0.2
d) 1.8

Explanation: As we know that ε/sp (1- ε) = 0.6/1.50(1-0.6) = 1.

5. ____ of the liquid is defined as volumetric flow rate of the liquid divided by the total area.
a) Final velocity
b) Total volume
c) Superficial velocity
d) Wetted perimeter

Explanation: The superficial velocity is defined as the volumetric rate and liquid divided by total or empty cross sectional area Usup.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. What does the below equation represent?

a) Resistance
c) Repulsion
d) Void age

Explanation: Here ε is the void fraction sometimes called porosity of the bed and Sp is the specific surface area of the particles.

7. What does the below represent?
t= f tc
a) Cake formation
b) Drum rotation
c) Initial extraction
d) Extra time

Explanation: The above equation represents the time taken for cake formation, if tc is the time for one full rotation of the drum.

8. ____ is defined as the volume of void filled and total volume.
a) Upper velocity
b) Saturation
c) Residual saturation
d) Superficial velocity

Explanation: The saturation (S) is usually defined with respect to the wetting fluid and is therefore the fractional volume of voids occupied by the wetting fluid.

9. ____ is the maximum volume wetted to ratio of total volume.
a) Residual saturation
b) Saturation
c) Residual saturation
d) Superficial velocity

Explanation: The residual saturation (SF) is defined as the ratio of maximum volume wetting fluid eliminated from flow and total volume of voids.

10. Calculate S, if the voids filled are 40 m3 and having 50 m3 of total volume?
a) 0.8
b) 1.25
c) 40
d) 50

Explanation: As we know that S = void volume/total volume = 40/50 = 0.8.

Sanfoundry Global Education & Learning Series – Mechanical Operations.

To practice all areas of Mechanical Operations, here is complete set of 1000+ Multiple Choice Questions and Answers.