Questions and answers for exam Preparation

MCQs

Total Questions : 234 | Page 1 of 24 pages

Question 1. Turbine impeller consists of flat impeller blades with

a vertical pitch welded directly to the shaft
a angled pitch welded directly to the shaft
a vertical pitch welded to a horizontal disk
a angled pitch welded to a horizontal disk

Discuss Question

Answer: Option C. -> a vertical pitch welded to a horizontal disk
Answer: (c).a vertical pitch welded to a horizontal disk

Question 2. Which of the following would be best described as an axial flow impeller?

An impeller with blades pitched at 45° to the vertical
An impeller which directs liquid flow towards the base of the reactor
Both (a) and (b)
An impeller with blades pitched at 75° to the vertical

Discuss Question

Answer: Option C. -> Both (a) and (b)
Answer: (c).Both (a) and (b)

Question 3. An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it

enhances bubble coalescence
causes bubbles to expand
discourages bubble coalescence
increases the surface tension of the liquid

Discuss Question

Answer: Option C. -> discourages bubble coalescence
Answer: (c).discourages bubble coalescence

Question 4. Vortexing in stirred tank reactors can be prevented by

installing baffles in the reactor
shifting the impeller to an off-centre position
Both (a) and (b)
using axial flow impellers

Discuss Question

Answer: Option C. -> Both (a) and (b)
Answer: (c).Both (a) and (b)

Question 5. Henry's law relates

the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
the oxygen transfer rate and the bubble size
the oxygen transfer rate and the temperature
the oxygen transfer rate to the partial pressure of oxygen in the liquid

Discuss Question

Answer: Option A. -> the partial pressure of oxygen and the saturation concentration of oxygen in the liquid
Answer: (a).the partial pressure of oxygen and the saturation concentration of oxygen in the liquid

Question 6. Pure oxygen, if used instead of air will increase oxygen transfer rates because

the saturation concentration of oxygen is higher
the bubble size is smaller
the oxygen transfer coefficient is larger
the partial pressure of oxygen in the gas phase is lower

Discuss Question

Answer: Option A. -> the saturation concentration of oxygen is higher
Answer: (a).the saturation concentration of oxygen is higher

Question 7. For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) co-relating power consumption (Pm) and fermenter volume (V) can be expressed as