Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Open and Closed Circuit Operation

1 - Question

When this interface approaches the layer of sediment, its rate of fall decreases until the _____
a) Final settling point
b) Critical settling point
c) Primer settling point
d) Kynch velocity

Explanation: The critical settling point is reached when a direct interface is formed between the sediment and the clear liquid.

2 - Question

What does the following equation represents?
μc = μ(1 + k’’C)

a) Einstein formula
b) Newton’s formula
c) Kynch formula
d) Neymar formula

Explanation: The above equation represents the Einstein formula for critical viscosity, where μ is the viscosity of fluid and k’’ is constant for a given shape.

3 - Question

The above below equation is used to calculate the _____

a) Rate of filtration
b) Rate of flotation
c) Rate of sedimentation
d) Rate of evaporation

Explanation: The above equation approximately gives the rate of sedimentation, where H is the height of the sludge line at time t and b is constant for a given separation.

4 - Question

The plot of ln (H-H) against t, remits ___
a) A straight line
b) An elliptical curve
c) A hyperbolic curve
d) A parabolic curve

Explanation: If ln (H − H) is plotted against t, a straight line of slope −b is obtained, the values of H are determined largely by the surface film of liquid adhering to the particles.

5 - Question

The aggregation of colloids is known as ____
a) Coagulation
b) Fluctuation
c) Sedimentation
d) Precipitation

Explanation: The aggregation of colloids is known as coagulation, or flocculation, particles dispersed in liquid media collide due to their relative motion.

6 - Question

Gravity thickening requires much higher torques than clarification.
a) True
b) False

Explanation: Yes, it requires much higher torques than clarification, while clarifiers frequently require the inclusion of special flocculating devices.

7 - Question

At what distance the plates are kept?
a) 10 – 50 mm
b) 5 – 40 mm
c) 20 – 50 mm
d) 1 – 4 mm

Explanation: Plates are placed at a distance of 5 to 40 mm, depending up on the conductivity of the liquid in use.

8 - Question

There will be no effect on rate of sedimentation, if ratio of diameter of vessel to particle is ___
a) <100
b) =100
c) >100
d) No effect

Explanation: If ratio of diameter of vessel to particle is greater than 100, then there is no wall effect to the rate of sedimentation but can affect for smaller values.

9 - Question

The higher the concentration, the lower the ____
a) Density
b) Rate of escaping
c) Speed
d) Rate of fall

Explanation: The higher the concentration, the lower will be the rate of fall of sludge line because the greater is upward velocity steeper the gradient.

10 - Question

The final consolidation is the ______ part.
a) Fastest
b) Slowest
c) Toughest
d) Extract