43.  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

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44. Which of the following stirrer requires least amount of energy for same yield?
A.Mig
B.Intermig
C.Turbine
D.Disc

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45. 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

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46. Pure oxygen, if used instead of air will increase oxygen transfer rates because
A.the saturation concentration of oxygen is higher
B.the bubble size is smaller
C.the oxygen transfer coefficient is larger
D.the partial pressure of oxygen in the gas phase is lower

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47. 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
A.kL ∝ (Pm/V)0.33
B.kL ∝ (Pm/V)0.66
C.kL ∝ (Pm/V)0.50
D.kL ∝ (Pm/V)

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48.  Higher temperatures affect oxygen transfer rates by
A.increasing KLa but lowering C*o
B.lowering KLa but increasing C*o
C.increasing KLa and increasing Co
D.lowering KLa and lowering Co

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49. The Intermig impeller is
A.an axial flow impeller which can be used for the culture of aerobic organisms
B.directed upwards rather than towards the base of the reactor
C.a fork shaped extensions to the impeller facilitate bubble break up
D.All of the above

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