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

b) Hydraulic radius

c) Repulsion

d) Void age

View Answer

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

_{H}.

2. What does the ε represents?

a) Porosity

b) Density

c) Viscosity

d) Acidity

View Answer

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 m^{2} and the void area is 100 m2?

a) 10.5

b) 0.45

c) 2.222

d) 0.89

View Answer

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

View Answer

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

View Answer

Explanation: The superficial velocity is defined as the volumetric rate and liquid divided by total or empty cross sectional area U

_{sup}.

6. What does the below equation represent?

a) Resistance

b) Hydraulic radius

c) Repulsion

d) Void age

View Answer

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 t_{c}

a) Cake formation

b) Drum rotation

c) Initial extraction

d) Extra time

View Answer

Explanation: The above equation represents the time taken for cake formation, if t

_{c}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

View Answer

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

View Answer

Explanation: The residual saturation (S

_{F}) 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 m^{3} and having 50 m^{3} of total volume?

a) 0.8

b) 1.25

c) 40

d) 50

View Answer

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

**Sanfoundry Global Education & Learning Series – Mechanical Operations.**

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