Agitation and Aeration problems
- 1. Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?
Options- 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 Discuss
Correct Answer: Moving through the bubble boundary layer
- 2. Penetration theory assumes that turbulent eddies travel from the bulk of the phase to the interface where they remain constant for a constant exposure time (te). The model correlating KL, mass transfer coefficient and DAB, diffusivity can be expressed as
Options- A. KL = 2(DAB/?te)0.25
- B. KL = 2(DAB/?te)0.5
- C. KL = 2(DAB/?te)0.75
- D. KL = 2(DAB/?te) Discuss
Correct Answer: KL = 2(DAB/?te)0.5
- 3. Surface renewal theory predicts that the mass transfer coefficient is
Options- A. directly proportional to the square root of the molecular diffusivity
- B. inversely proportional to the square root of the molecular diffusivity
- C. directly proportional to the cube root of the molecular diffusivity
- D. indirectly proportional to the cube root of the molecular diffusivity Discuss
Correct Answer: directly proportional to the square root of the molecular diffusivity
- 4. Which of the following would be best described as an axial flow impeller?
Options- A. An impeller with blades pitched at 45° to the vertical
- B. An impeller which directs liquid flow towards the base of the reactor
- C. Both (a) and (b)
- D. An impeller with blades pitched at 75° to the vertical Discuss
Correct Answer: Both (a) and (b)
- 5. Which of the following type(s) of stirrer can be used for microbiological processes?
Options- A. Mig
- B. Intermig
- C. Turbine
- D. All of these Discuss
Correct Answer: All of these
- 6. Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
Options- A. Addition of antifoams
- B. Increase in temperature
- C. Increase in stirrer speed
- D. Both (a) and (b) Discuss
Correct Answer: Increase in stirrer speed
- 7. Which of the following will have the highest surface area available for oxygen transfer?
Options- 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 Discuss
Correct Answer: A sparged stirred tank reactor agitated at 400 rpm
- 8. At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry's law constant will be
Options- A. 0.793atml/mmol
- B. 0.207atml/mmol
- C. 1.26 atml/mmol
- D. 8.74 atml/mmol Discuss
Correct Answer: 0.793atml/mmol
- 9. The oxygen transfer rate in a bioreactor will increase if
Options- A. oil is added
- B. antifoam is added
- C. detergent like molecules are added
- D. increase in the reactor temperature Discuss
Correct Answer: detergent like molecules are added
- 10. Power number is expressed as
Options- A. P0 / N2Di3?
- B. P0 / N3Di5?
- C. P0 / N3Di3?
- D. P0 / N2Di2? Discuss
Correct Answer: P0 / N3Di5?
Programming
Copyright ©CuriousTab. All rights reserved.