15. For the turbulent flow, the dispersion coefficient is correlated as a function of

A.Reynolds number

B.Sherwood number

C.Schmidt number

D.Grashof number

16. In sterilization process, spore of which of the following organism is considered as control?

A.Bacillus subtilis

B.Clostridium botulinum

C.Bacillus stearothermophilus

D.Aspergillus niger

17. Analogus to the molecular diffusion, the x-directional flux of microorganisms suspended in a medium due to the axial mixing can be represented as (where Jn is flux component 'n', cn is concentration of'n')

A.Jn = -dcn/dx

B.Jn = dcn/dx

C.Jn = -D dcn/dx

D.Jn = D dcn/dx

18. The typical size of particles collected by diffusion mechanism is

A.<0.25μm

B.<0.5μm

C.<0.75μm

D.<1μm

19. The X90 value for a filtration system is

A.The time required to reduce microbial population by 90%

B.the time required to traverse survivor curve by one log cycle.

C.the depth required to reduce population by 90%

D.the depth of the filter required to reduce population by 99%

20. The value of K

A.increases with increase in air velocity

B.decreases with increase in air velocity

C.increases to an optimum with increase in air velocity and decreases on further increase of air velocity

D.none of these

21. Model proposed by the Friedlander, correlating the air filtration efficiency by impaction can be expressed as (where NSt is the Stokes number)

A.ηimp = 0.075NSt1.2

B.ηimp = 0.75NSt1.2

C.ηimp = 0.25NSt1.2

D.ηimp = 0.025NSt1.2

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