# Mechanical Operations Questions and Answers – Classification of Solid Particles

This set of Mechanical Operations Quiz focuses on “Classification of Solid Particles”.

1. The underflow ratio is defined as ___
a) D/E
b) B/F
c) E/F
d) D/F

Explanation: The overflow ratio is defined as the ratio of mass flow rate F and the mass flow rate of underflow i.e. D, so D/F.

2. Calculate the overflow ratio, if the mass fraction in feed is 0.635 and fraction in overflow is 0.945, while in underflow is 0.285?
a) 0.85
b) 0.66
c) 0.75
d) 0.50

Explanation: As D/F = Xf –Xd/Xd – Xb = (0.635 – 0.285)/ (0.945 – 0.285) = 0.66.

3. Calculate the underflow, if overflow is given as 0.45?
a) 0.34
b) 0.55
c) 0.33
d) 0.55

Explanation: As B/F = 1- (D/F) = 1 -0.45 = 0.55.

4. The effectiveness E can be defined as ____
a) FXD/ BXD
b) BXD/FXF
c) DXD/FXF
d) BXD/ DXF

Explanation: The screen effectiveness E = DXD/FXF, which is the ratio of oversized material in overflow and the amount that entering in the feed.

5. Calculate E, if the D/F ratio is 1.2 and amount of overflow and feed is 0.33 and 0.45?
a) 0.85
b) 0.55
c) 0.88
d) 0.80

Explanation: As we know E = E = DXD/FXF = 1.33 (0.33/0.45) = 0.88.

6. Separation of a solid from suspension in liquid by screen means is called as _____
a) Sedimentation
b) Extraction
c) Distillation
d) Leaching

Explanation: The separation of solids from a suspension in liquid by means of porous medium or screen which retains the solids and allows the liquid to pass is known as filtration.

7. Which of the following is not a driving force used for filtration?
a) Gravity
b) Atmospheric pressure
c) Centrifugal force
d) Drag force

Explanation: Drag force cannot be implied for separation technique that used in filtration, filtrate is forced through porous medium by gravity, super atmospheric pressure or downstream centrifugal force.

8. Filter medium filtration is also called ____
a) Locking
b) Blocking
c) Chapping
d) Chipping

Explanation: The mechanism in which the solids are trapped within the pores of medium leads to the filter medium filtration also called as blocking.

9. The properties like viscosity, density, corrosion are important while selecting equipment’s.
a) False
b) True

Explanation: The properties like viscosity, density, corrosion and also shape, size distribution and packing are important while selecting equipment’s.

10. If the filtration pressure is constant, the rate of flow will _____
a) Increase
b) Diminish
c) Stop
d) Be constant

Explanation: If the filtration pressure is constant, the rate of flow will progressively diminish, whereas if flow rate is to be maintained constant.

Sanfoundry Global Education & Learning Series – Mechanical Operations.

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