Mechanical Operations MCQs

Question 1

__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.

Accepted Answer

Minimum size

Answer

Cast iron

Answer

Maximum size

Answer

Elliptical

Question 2

Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is

Accepted Answer

All of the above

Answer

Added to the feed slurry

Answer

Precoated on the filter medium prior to filtration

Answer

Separated from the cake by dissolving solids or by burning it off

Question 3

As per Taggart's formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms)

Accepted Answer

93 LS

Answer

LS

Answer

250 LS

Answer

$$\sqrt {{	ext{LS}}} $$

Question 4

Solid particles separation based on the difference in their flow velocities through fluids is termed as the

Accepted Answer

Classification

Answer

Clarification

Answer

Elutriation

Answer

Sedimentation

Question 5

Sauter mean diameter is the same as the __________ mean diameter.

Accepted Answer

Volume-surface

Answer

Mass

Answer

Arithmetic

Answer

Geometric

Question 6

Filtration rate through a filter cake is proportional to (where, S = filtering surface, R = specific cake resistance, $$\mu $$ = viscosity of the filtrate)

Accepted Answer

All of the above

Answer

S

Answer

$$\frac{1}{{	ext{R}}}$$

Answer

$$\frac{1}{\mu }$$

Question 7

Ribbon blenders are exclusively meant for

Accepted Answer

Non-flowing powder and thin pastes

Answer

Blending miscible liquids

Answer

Bath mixing

Answer

Continuous mixing

Question 8

Driving force in case of filtration by a centrifuge is the

Accepted Answer

Centrifugal pressure exerted by the liquid

Answer

Speed of the centrifuge

Answer

Narrow diameter of the vessel

Answer

Formation of highly porous cake

Question 9

Sphericity of pulverised coal is

Accepted Answer

<1

Answer

1

Answer

>1

Answer

∞