200 Best MCQs on Agitation and aeration- biochemical engineering

Q33). Power consumption by agitation is

a).a function of physical properties
b).a function of operating conditions
c).a function of vessel and impeller geometry
d).all of the above

Correct Answer:
all of the above
Explaination:

Q34). Which of the following impellers will provide radial flow?

a).Paddles
b).Flat blade turbines
c).Disk flat blade turbines
d).All of the above

Correct Answer:
All of the above
Explaination:

Q35). When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?

a).If the stirrer speed is increased, the rate will be faster
b).Baffles in the tank will increase the rate of cooling
c).Faster cooling rates at a slower rate of pumping
d).Faster cooling rates at a faster rate of pumping

Correct Answer:
Faster cooling rates at a slower rate of pumping
Explaination:

Q36). When the height of an aerated bioreactor is increased, it will increase the oxygen transfer rate by

a).increasing the partial pressure of oxygen at the base of the reactor
b).decreasing the saturation concentration of oxygen in the reactor
c).decreasing the gas-holdup
d).all of the above

Correct Answer:
increasing the partial pressure of oxygen at the base of the reactor
Explaination:

Q37). Which of the following is correct for the off-centre impellers?

a).Off-centre impellers can be used with any size reactor
b).Off-centre impellers should only be used with reactors with volumes less than 10 m^3
c).The impeller should never be placed in an off-centre position
d).Off-centre impellers can be used when volume is greater than 10 m^3

Correct Answer:
Off-centre impellers should only be used with reactors with volumes less than 10 m^3
Explaination:

Q38). The power required by an impeller in a gas sparged system compare to the power required by impeller operating at same speed in a gas free liquid is usually

a).lesser
b).higher
c).same
d).may be lesser or higher depending upon the geometry

Correct Answer:
lesser
Explaination:

Q39). Which of the following stirrer requires least amount of energy for same yield?

a).Mig
b).Intermig
c).Turbine
d).Disc

Correct Answer:
Intermig
Explaination:

Q40). A reactor has a total volume of 50,000 litres. If it has a headspace volume of 10,000 litres, then volume of liquid in the reactor will be

a).10,000 l
b).20,000 l
c).30,000 l
d).40,000 l

Correct Answer:
40,000 l
Explaination: