200 Best MCQs on Agitation and aeration- biochemical engineering

Q9). Why vortexing is undesirable in the agitation of biological systems?

a).The collision between the cells, impeller and air bubbles will lead to cell damage
b).Poor mixing despite the use of high stirrer speeds
c).Mixing will not be in the turbulent region
d).All of the above

Correct Answer:
All of the above
Explaination:


Q10). The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through

a).gas-liquid interface
b).bubble boundary layer
c).bulk liquid
d).gas phase

Correct Answer:
bubble boundary layer
Explaination:


Q11). Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?

a).Moving through the gas liquid interface
b).Moving through the bubble boundary layer
c).Moving across the cell membrane
d).Moving through the bulk liquid

Correct Answer:
Moving through the bubble boundary layer
Explaination:


Q12). If liquid density and viscosity remains constant, then the Reynolds number in a stirred tank reactor will vary with the

a).impeller diameter
b).square root of the impeller diameter
c).square of the impeller diameter
d).cube of the impeller diameter

Correct Answer:
square of the impeller diameter
Explaination:


Q13). What is the ratio of depth of liquid in vessel to the diameter of tank (H:Dt)?

a). 1:1
b). 2:1
c). 3:1
d).none of these

Correct Answer:
1:1
Explaination:


Q14). Radial flow impellers

a).provide high shear conditions for breaking up bubbles
b).direct flow towards the walls of the reactor
c).Both (a) and (b)
d).provide low shear conditions and are suited for use in shear sensitive procesess

Correct Answer:
Both (a) and (b)
Explaination:


Q15). Transient flow range of mixing speed is obtained for

a).Rei<10
b).10c).Rei>10^4
d).None of these

Correct Answer:
10 Explaination:


Q16). A typical ceiling fan would be best described as a(n)

a).radial flow impeller
b).axial flow impeller
c).intermig impeller
d).Rushton turbine

Correct Answer:
axial flow impeller
Explaination:


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