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Home⇒ Engineering⇒
Mass transfer
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 ⇒ Which of the following solutions will follow Raoult's law most closely ? A solution of benzene, toluene and oxylene. [other wrong options] [Discuss in forum] 35% solution of camphor in water. 35% solution of NH3 in water. A solution of polar organic compounds (not of homologs of a series). |
Q22 ⇒ Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. Reynolds number in mass transfer is analogous to Grashoff number in heat transfer. [other wrong options] [Discuss in forum] Sherwood number in mass transfer is analogous to Nusselt number in heat transfer. Prandtl number in heat transfer is analogous to Schmidt number in mass transfer. Reynolds number remains the same in both heat and mass transfer. |
Q23 ⇒ Pick out the wrong statement. Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum. [other wrong options] [Discuss in forum] Critical moisture content is not a property of the material itself. A sharp increase in pressure drop gives an indication of the flooding in a distillation column. Separation of components is not possible in liquid extraction, if selectivity is unity. |
Q24 ⇒ The relative volatility of a binary mixture at the azeotropic composition is 1 [other wrong options] [Discuss in forum] > 1 0 ∞ |
Q25 ⇒ At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is 0.4 [other wrong options] [Discuss in forum] 0 0.2 1 |
Q26 ⇒ Separation of __________ employs gaseous diffusion process. isotopes of uranium [other wrong options] [Discuss in forum] N2 and O2 from air isotopes of helium SO2 and air |
Q27 ⇒ The binary diffusivity in gases at atmospheric conditions is about 10-1 cm2/sec [other wrong options] [Discuss in forum] 10-9 cm/sec 10-3 sec/cm 10-4 cm2/sec2 |
Q28 ⇒ Pick out the wrong statement pertaining to the cooling towers. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature. [other wrong options] [Discuss in forum] In case of induced draft cooling tower, the fan is placed at the top of the tower. Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and hot discharged air. A natural draft cooling tower is recommended to be used, when the air humidity is low and air temperature is also low. |
Q29 ⇒ The minimum number of theoretical plates is required for achieving a given separation in distillation column with total reflux [other wrong options] [Discuss in forum] no reflux zero reflux ratio minimum reflux ratio |
Q30 ⇒ Large scale usage of flash distillation is practised in petroleum refinning [other wrong options] [Discuss in forum] soap manufacturing ammonia synthesis plant polymerisation industry |
Q31 ⇒ Prandtl number for water at 20°C is about 7 [other wrong options] [Discuss in forum] 70 0.7 150 |
Q32 ⇒ An example of elutioh is separation of uranium oxide from its ore by H2SO4 in a Pachuca tank. [other wrong options] [Discuss in forum] separation of sugar from sugar beet by hot water. dissolution of tannin out of tree barks by water. recovery of vegetable oils from seeds. |
Q33 ⇒ The cooling effect in a cooling tower can not be increased by none of these. [other wrong options] [Discuss in forum] increasing the air velocity over the wet surfaces. reducing the humidity of entering air. lowering the barometric pressure. |
Q34 ⇒ Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. bound [other wrong options] [Discuss in forum] unbound critical none of these |
Q35 ⇒ Use of natural draft cooling tower is practised, when the air has low both 'a' & 'b' [other wrong options] [Discuss in forum] humidity temperature neither 'a' nor 'b' |
Q36 ⇒ Flooding results in low tray efficiency [other wrong options] [Discuss in forum] high tray efficiency high gas velocity good contact between the fluids |
Q37 ⇒ With increase in temperature, the rate of leaching increases, because the diffusivity of solute increases. [other wrong options] [Discuss in forum] viscosity of solvent decreases. thermal conductivity of solute increases. none of these. |
Q38 ⇒ The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature. none of these [other wrong options] [Discuss in forum] dew point wet bulb dry bulb |
Q39 ⇒ The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp = M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force.) Kc = Kp . RT = Km . RT/p [other wrong options] [Discuss in forum] Kc = Kp = Km Kc = Kp/RT = Km . RT/P none of these |
Q40 ⇒ The vapour pressure exerted by the moisture contained in a wet solid depends upon the all (a), (b) and (c). [other wrong options] [Discuss in forum] nature of the moisture. temperature. nature of the solid. |
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