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Objective Type Set
Online MCQ Assignment
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1. 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

Answer: b [Reason:] The critical settling point is reached when a direct interface is formed between the sediment and the clear liquid.

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

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

Answer: a [Reason:] 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. 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

Answer: c [Reason:] 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. 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

Answer: a [Reason:] 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. The aggregation of colloids is known as ____
a) Coagulation
b) Fluctuation
c) Sedimentation
d) Precipitation

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

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

Answer: a [Reason:] Yes, it requires much higher torques than clarification, while clarifiers frequently require the inclusion of special flocculating devices.

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

Answer: b [Reason:] Plates are placed at a distance of 5 to 40 mm, depending up on the conductivity of the liquid in use.

8. 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

Answer: c [Reason:] 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. The higher the concentration, the lower the ____
a) Density
b) Rate of escaping
c) Speed
d) Rate of fall