Agitation and Aeration – Section 1

36. Which of the following will have the highest surface area available for oxygen transfer?

A. A shake flask
B. A standing test tube
C. A non-sparged stirred tank reactor agitated at 400 rpm
D. A sparged stirred tank reactor agitated at 400 rpm

Correct Answer: D. A sparged stirred tank reactor agitated at 400 rpm

37. A flooded impeller will lead to poor oxygen transfer rates because

A. bubbles tend to coalesce under the impeller
B. bubbles tend to break down too rapidly under high shear conditions
C. bubbles tend to move too quickly through the bulk liquid
D. the cells clog up the surface of the bubble

Correct Answer: A. bubbles tend to coalesce under the impeller

38. 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: D. all of the above

39. 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: D. All of the above

40. When the liquid is pumped through a 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: C. Faster cooling rates at a slower rate of pumping

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