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Home⇒ Medical Science⇒ Bochemical Engineering⇒ Agitation and aeration
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ The power required by an agitator operating in a gas-sparged system is lesser than the power required by an impeller in operating at same speed in a gas free system [other wrong options] [Discuss in forum] more than the power required by an impeller in operating at same speed in a gas free system same as the power required by an impeller in operating at same speed in a gas free system none of the above |
Q22 ⇒ The power consumption in a stirring vessel can be assessed by using a all of these [other wrong options] [Discuss in forum] dynamometer strain gauge attached to agitator shaft watt meter attached to agitator motor |
Q23 ⇒ 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 KL = 2(DAB/πte)0.5 [other wrong options] [Discuss in forum] KL = 2(DAB/πte)0.25 KL = 2(DAB/πte)0.75 KL = 2(DAB/πte) |
Q24 ⇒ The reason of using a flat disk in a Turbine is to ensure that the bulk of the energy consumption occurs at the blades [other wrong options] [Discuss in forum] to create high shear conditions to break up bubbles more efficiently than the impeller blades all of the above |
Q25 ⇒ Turbine impeller consists of flat impeller blades with a vertical pitch welded to a horizontal disk [other wrong options] [Discuss in forum] a vertical pitch welded directly to the shaft a angled pitch welded directly to the shaft a angled pitch welded to a horizontal disk |
Q26 ⇒ Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions? Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor [other wrong options] [Discuss in forum] Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor Both (a) and (b) Axial flow impellers provide low shear, energy efficient mixing conditions |
Q27 ⇒ Which of the following stirrer requires least amount of energy for same yield? Intermig [other wrong options] [Discuss in forum] Mig Turbine Disc |
Q28 ⇒ Flooding is a condition/phenomenon which occur in a bioreactor when The air escapes without being distributed by the agitator [other wrong options] [Discuss in forum] The fermenter medium spills out the reactor due to foaming The volume of foam is more than the volume of broth None of the above |
Q29 ⇒ The oxygen absorption rate can be determined by all of these [other wrong options] [Discuss in forum] sodium sulfite oxidation method dynamic gassing out technique direct measurement |
Q30 ⇒ Larger propellers turn at the speed of 400 to 800 rpm [other wrong options] [Discuss in forum] 20 to 150 rpm 150 to 300 rpm 1150 rpm |
Q31 ⇒ Small propellers turn at the speed of either 1150 rpm or 1750 rpm [other wrong options] [Discuss in forum] 20 or 150 rpm 150 or 300 rpm 400 or 800 rpm |
Q32 ⇒ Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because all of the above [other wrong options] [Discuss in forum] it decrease the bubble size it decreases the size of the boundary layer surrounding a bubble it increases the rate of movement of oxygen molecules through the bulk liquid |
Q33 ⇒ Which of the following number is calculated from the diameter and peripheral speed of the impeller? Reynolds number [other wrong options] [Discuss in forum] Froude number Power number None of these |
Q34 ⇒ Swirling and vortex formation can be prevented by both (a) and (b) [other wrong options] [Discuss in forum] using baffles using diffusion ring with turbines none of these |
Q35 ⇒ Why vortexing is undesirable in the agitation of biological systems? All of the above [other wrong options] [Discuss in forum] The collision between the cells, impeller and air bubbles will lead to cell damage Poor mixing despite the use of high stirrer speeds Mixing will not be in the turbulent region |
Q36 ⇒ A typical ceiling fan would be best described as a(n) axial flow impeller [other wrong options] [Discuss in forum] radial flow impeller intermig impeller Rushton turbine |
Q37 ⇒ 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 0.793atml/mmol [other wrong options] [Discuss in forum] 0.207atml/mmol 1.26 atml/mmol 8.74 atml/mmol |
Q38 ⇒ The average fractional gas hold up (H) can be given as (where Zf and Zl are the level of aerated and clear liquid respectively) H = (Zf-Zl)/Zf [other wrong options] [Discuss in forum] H = Zf/Zl H = Zf/ZfZl H =(Zf+Zl)/Zf |
Q39 ⇒ Which of the following is correct for the off-centre impellers? Off-centre impellers should only be used with reactors with volumes less than 10 m3 [other wrong options] [Discuss in forum] Off-centre impellers can be used with any size reactor The impeller should never be placed in an off-centre position Off-centre impellers can be used when volume is greater than 10 m3 |
Q40 ⇒ Which of the following is not classified as an axial flow impeller? A Rushton turbine [other wrong options] [Discuss in forum] A propeller A marine impeller A hydrofoil impeller |
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