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Question: If the stirring speed increased from 300 to 500 rpm leads to an increase in the reaction rate by two folds. Then it may be concluded that
[A].

the reaction was mass transfer limited at 300 rpm

[B].

the reaction was mass transfer limited at 500 rpm

[C].

the reaction did not involve any mass transfer step

[D].

the movement of molecules in the reactor at 300 rpm occurred due to diffusion alone

Answer: Option A

Explanation:

No answer description available for this question.

Question: The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by
[A].

ultra-small dissolved oxygen probes

[B].

laser based photographic systems

[C].

measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor

[D].

measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor

Answer: Option C

Explanation:

No answer description available for this question.

Question: The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?
[A].

The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium

[B].

The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer

[C].

The growth rate is neither mass transfer nor kinetically limited

[D].

No conclusion on the growth rate can be withdrawn

Answer: Option D

Explanation:

No answer description available for this question.

Question: An increase in the heat transfer in the stirred tank reactor will be observed at
[A].

higher cooling water temperature

[B].

higher stirrer speed

[C].

the removal of baffles from the reactor

[D].

slower stirrer speed

Answer: Option B

Explanation:

No answer description available for this question.

Question: 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

Answer: Option C

Explanation:

No answer description available for this question.

Question: A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
[A].

zero

[B].

15 mg.l-1.s-1

[C].

10 mg.l-1.s-1

[D].

5 mg.l-1.s-1

Answer: Option B

Explanation:

No answer description available for this question.

Question: The oxygen transfer rate in a bioreactor will increase if
[A].

oil is added

[B].

antifoam is added

[C].

detergent like molecules are added

[D].

increase in the reactor temperature

Answer: Option C

Explanation:

No answer description available for this question.

Question: Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
[A].

Addition of antifoams

[B].

Increase in temperature

[C].

Increase in stirrer speed

[D].

Both (a) and (b)

Answer: Option C

Explanation:

No answer description available for this question.

Question: 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

Answer: Option B

Explanation:

No answer description available for this question.

Question: A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to
[A].

zero

[B].

3 mg.l-1.s-1

[C].

5 mg.l-1.s-1

[D].

15 mg.l-1.s-1

Answer: Option A

Explanation:

No answer description available for this question.