Mechanical Operations MCQs

Question 1

Filtrate flow rate in case of a rotary drum vacuum filter (in which R m << R c ) is proportional to __________ and the cycle time (where, $$\mu $$ = filtrate viscosity, R m = filter medium resistance, R c = cake resistance ).

Accepted Answer

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

Answer

$$\sqrt \mu $$

Answer

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

Answer

$$\frac{1}{{{\mu ^2}}}$$

Question 2

A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is

Accepted Answer

$$\frac{1}{2}$$w 2 .δ.ρL(2R + δ)

Answer

$$\frac{1}{2}$$w 2 .R 2 .ρL

Answer

$$\frac{1}{2}$$w 2 .δ 2 .ρL

Answer

$$\frac{1}{2}$$w 2 .R.ρL(R + 2δ)

Question 3

All resistances during washing of cake

Accepted Answer

Remain constant

Answer

Increases

Answer

Decreases

Answer

None of these

Question 4

Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.

Accepted Answer

Screw

Answer

Flight

Answer

Slat or drag

Answer

Ribbon

Question 5

Pick out the correct statement:

Accepted Answer

Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products

Answer

The operating cost of shaking screen is more than that of a vibrating screen

Answer

Screen capacity does not depend upon the specific gravity of the minerals

Answer

Asphalt is best crushed using toothed roll crusher

Question 6

Crushing efficiency is the ratio of the

Accepted Answer

Surface energy created by crushing to the energy absorbed by the solid

Answer

Energy absorbed by the solid to that fed to the machine

Answer

Energy fed to the machine to the surface energy created by crushing

Answer

Energy absorbed by the solid to the surface energy created by crushing

Question 7

Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is

Accepted Answer

<10

Answer

>10

Answer

>100

Answer

<100

Question 8

Float and sink test determines the possibility of cleaning of coal by a process based on the

Accepted Answer

Gravity separation

Answer

Wettability

Answer

Particle shape

Answer

None of these

Question 9

The grinding in a hammer crusher takes place due to the

Accepted Answer

Both A & B

Answer

Attrition

Answer

Impact

Answer

Neither A nor B