50. Main reason for using baffles in stirred tank reactors are
A.baffles permit turbulence conditions to arise at low stirrer speed
B.baffles will allow axial mixing to occur even with radial flow impellers
C.both (a) and (b)
D.baffles prevent turbulent conditions in stirred tank reactors

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51. Which of the following is not classified as an axial flow impeller?
A.A propeller
B.A marine impeller
C.A Rushton turbine
D.A hydrofoil impeller

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52. Power number (Np) is also known as
A.Froude's number
B.Bond's number
C.Newton's number
D.Rayleigh's number

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53. Flooding is a condition/phenomenon which occur in a bioreactor when
A.The air escapes without being distributed by the agitator
B.The fermenter medium spills out the reactor due to foaming
C.The volume of foam is more than the volume of broth
D.None of the above

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54.  A cylindrical reactor has a liquid volume of 100,000 litres. It has an aspect ratio the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:
A.1.0 m
B.3.0 m
C.5.0 m
D.7.0 m

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55. Detergent like substances produced by microorganisms during a fermentation will lead to
A.decrease the surface tension of the liquid
B.accumulate at the gas liquid interface
C.decrease the rate of bubble coalescence
D.all of the above

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56. A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:
A.1.3 m
B.3.3 m
C.5.3 m
D.7.3 m

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