MCQOPTIONS
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MCQOPTIONS
This section includes 854 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, = = __________ |
| A. | 1 |
| B. | 0.5 |
| C. | 10 |
| D. | 0 |
| Answer» B. 0.5 | |
| 2. |
In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTU __________ the absorption factor. |
| A. | increases with increase in |
| B. | is one at unity value of |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 3. |
Mass transfer co-efficient () and diffusivity () are related according to film theory as |
| A. | ∝ |
| B. | ∝ |
| C. | ∝ |
| D. | ∝ |
| Answer» B. ∝ | |
| 4. |
Absorption factor is defined as (where, = slope of the operating line = slope of the equilibrium curve) |
| A. | / |
| B. | / |
| C. | - |
| D. | x |
| Answer» C. - | |
| 5. |
In gas-liquid contact operation, the number of ideal stages, . This is true when the stripping factor '' is |
| A. | S > 1 |
| B. | S < 1 |
| C. | S = 1 |
| D. | S = ∞ |
| Answer» B. S < 1 | |
| 6. |
Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled |
| A. | and humidified. |
| B. | and dehumidified with increase in wet bulb temperature. |
| C. | at the same relative humidity. |
| D. | and dehumidified with decrease in wet bulb temperature. |
| Answer» E. | |
| 7. |
According to Poiseuille's law, the permeability for gas flow through a capillary is proportional to (where, μ = gas viscosity) |
| A. | μ |
| B. | 1/μ |
| C. | μ |
| Answer» C. μ | |
| 8. |
HS is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of HS has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in metres) corresponding to an operating line given by, y = 5x + 0.001 is |
| A. | 2.0 |
| B. | 1.56 |
| C. | 1.0 |
| D. | 0.56 |
| Answer» B. 1.56 | |
| 9. |
Nitrobenzene (boiling point = 210.6°C) is steam distilled at 1 atm pressure.Nitrobenzene will distill off __________ °C. |
| A. | at < 100 |
| B. | at > 210.6 |
| C. | between 100 and 210 |
| D. | none of these |
| Answer» B. at > 210.6 | |
| 10. |
An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is |
| A. | 0.048 |
| B. | 0.079 |
| C. | 0.122 |
| D. | 0.152 |
| Answer» E. | |
| 11. |
The wet and 'dry bulb temperature for a vapour-gas mixture are 25°C and 30°C respectively. If the mixture is heated to 45°C at constant pressure, the wet bulb temperature will be __________ °C. |
| A. | 25 |
| B. | > 25 |
| C. | < 25 |
| D. | - 25 |
| Answer» C. < 25 | |
| 12. |
The value of /( + ), for steady state equimolal counter diffusion of two gases '' and '' is |
| A. | 1 |
| B. | ∞ |
| C. | 0.5 |
| D. | 2 |
| Answer» C. 0.5 | |
| 13. |
A mixture of 10% CH vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around __________ °C. |
| A. | 21.7 |
| B. | 20 |
| C. | 27.3 |
| D. | 18.7 |
| Answer» E. | |
| 14. |
factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by |
| A. | = 2 |
| B. | = 2 |
| C. | = 2 |
| D. | none of these |
| Answer» B. = 2 | |
| 15. |
In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads ?Reflux conditions:(i) Reflux stream is completely liquid and is at its bubble point. (ii) Reflux stream is below its bubble point. |
| A. | Condenser and reboiler loads are the same in both the cases. |
| B. | Reboiler load is the same in both the cases but condenser load is higher in case (ii). |
| C. | Condenser load is the same in both the cases but reboiler load is higher in case (ii). |
| D. | Both condensor and reboiler loads are higher in case (ii) as compared to case (i). |
| Answer» E. | |
| 16. |
Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C? |
| A. | Humidification only |
| B. | Heating only |
| C. | Both heating and humidification |
| D. | Evaporative cooling |
| Answer» D. Evaporative cooling | |
| 17. |
Mass transfer co-efficient is directly proportional to according to the __________ theory. |
| A. | film |
| B. | penetration |
| C. | surface-renewal |
| D. | none of these |
| Answer» B. penetration | |
| 18. |
/is the expression for |
| A. | absorption factor |
| B. | Brinkman number |
| C. | slope of operating line in absorber |
| D. | slope of operating line in stripper. |
| Answer» B. Brinkman number | |
| 19. |
In case of gases, the binary diffusivity is proportional to (where, = pressure) |
| A. | 1/ |
| B. | 1/ |
| Answer» C. | |
| 20. |
(/.) is termed in mass transfer operation as the |
| A. | Stanton number |
| B. | Peclet number |
| C. | thermal diffusivity |
| D. | momentum diffusivity |
| Answer» B. Peclet number | |
| 21. |
CO can be absorbed by |
| A. | hot cupric oxide |
| B. | heated charcoal |
| C. | cold Ca(OH) |
| D. | alumina |
| Answer» C. cold Ca(OH) | |
| 22. |
The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient () for the same sytem is |
| A. | 100 |
| B. | 10 |
| C. | 5 |
| D. | 1 |
| Answer» C. 5 | |
| 23. |
Which of the following is a suitable absorbent for removal of HS from natural gas ? |
| A. | Vetrocoke solution |
| B. | Monoethanol amine (MEA) |
| C. | Dilute |
| D. | Hot water |
| Answer» C. Dilute | |
| 24. |
Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (y = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (y/y).For 98% recovery of acetone, the number of trays required is/are |
| A. | 1 |
| B. | 8 |
| C. | 9 |
| D. | 10 |
| Answer» D. 10 | |
| 25. |
1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is |
| A. | 0.4 |
| B. | 0.25 |
| C. | 0.2 |
| D. | 0.175 |
| Answer» D. 0.175 | |
| 26. |
Experiments were conducted to determine the flux of a species in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10 kg mole/m.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m .s) for bulk concentrations of in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is |
| A. | 5.6 x 10 |
| B. | 8.5 x 10 |
| C. | 5.6 x 10 |
| D. | 8.5 x 10 |
| Answer» C. 5.6 x 10 | |
| 27. |
The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m/m) |
| A. | 500 |
| B. | 1200 |
| C. | 900 |
| D. | 800 |
| Answer» B. 1200 | |
| 28. |
The value of / ratio for economical absorption operation ranges from |
| A. | 0.5 to 0.8 |
| B. | 0.8 to 1.2 |
| C. | 1.25 to 2.0 |
| D. | 2.5 to 3.5 |
| Answer» D. 2.5 to 3.5 | |
| 29. |
The rough value of diffusion co-efficient of water vapor into air at 25°C may be about __________ cm/sec. |
| A. | 0.25 |
| B. | 2.5 |
| C. | 1.25 |
| D. | 0.0025 |
| Answer» B. 2.5 | |
| 30. |
/ is called the |
| A. | psychrometric ratio |
| B. | Lewis number |
| C. | Sherwood number |
| D. | Stantan number |
| Answer» C. Sherwood number | |
| 31. |
According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (α = 2) does not change appreciably in the coloumn. |
| A. | 5 |
| B. | 9 |
| C. | 12 |
| D. | 28 |
| Answer» D. 28 | |
| 32. |
According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, = molecular diffusivity) |
| A. | 1/ |
| Answer» B. | |
| 33. |
Which of the following liquid temperature (T) Vs. vapor-gas mixture enthalpy (H) diagram is valid for humidification operation? |
| A. | none of these. |
| Answer» C. | |
| 34. |
The individual mass transfer co-efficients (moles/m . s) for absorption of a solute from a gas mixture into a liquid solvent are, = 4.5 and = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ? |
| A. | liquid side |
| B. | gas side |
| C. | interfacial |
| D. | both liquid and gas side |
| Answer» C. interfacial | |
| 35. |
With increase in gas rate, the number of transfer units, , for a fixed degree of absorption by a fixed amount of solvent |
| A. | increases |
| B. | decreases |
| C. | decreases linearly |
| D. | remains unaffected |
| Answer» B. decreases | |
| 36. |
At equilibrium the concentration of water in vapour phase (C)in kg/m 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 100m 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 |
| A. | 0.0 |
| B. | 0.2 |
| C. | 0.4 |
| D. | 1.0 |
| Answer» D. 1.0 | |
| 37. |
For the case of flow of air past a wet bulb thermometer (air water vapour system), the approximate value of /. is around |
| A. | 0.60 |
| B. | 0.24 |
| C. | 1 |
| D. | 0.72 |
| Answer» D. 0.72 | |
| 38. |
The value of /( + ) for steady state molecular diffusion of gas '' through non-diffusing gas '' is |
| A. | 1 |
| B. | ∞ |
| C. | 0.5 |
| D. | 2 |
| Answer» B. ∞ | |
| 39. |
Weight of 1 m of humid air as compared to 1 m of dry air, under the same conditions, is |
| A. | less |
| B. | more |
| C. | same |
| D. | unpredictable |
| Answer» B. more | |
| 40. |
The diffusivity () in a binary gas mixture is related to the pressure () as |
| A. | ∝ |
| Answer» D. | |
| 41. |
When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system, |
| A. | as the acetone concentration increases, the solubility curves approach each other. |
| B. | both the phases become identical at a particular common point on both the solubility curves called the plait point. |
| C. | the distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption terminates on the x = y diagonal at the concentration of the plait point. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 42. |
Deairation (removal of O) of water is done by |
| A. | rectification |
| B. | absorption |
| C. | ion-exchange |
| D. | adsorption |
| Answer» D. adsorption | |
| 43. |
The equation, is for |
| A. | Fick's second law of diffusion. |
| B. | stready state diffusion for stagnant case. |
| C. | liquid M.T.C. by Higbie penetration theory. |
| D. | none of these. |
| Answer» C. liquid M.T.C. by Higbie penetration theory. | |
| 44. |
If = insoluble gas in gas stream and = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is |
| A. | / |
| B. | / |
| C. | always < 1 |
| D. | none of these |
| Answer» B. / | |
| 45. |
Molecular seives are regenerated by heating to __________ °C. |
| A. | < 150 |
| B. | 200-330 |
| C. | > 500 |
| D. | > 1000 |
| Answer» C. > 500 | |
| 46. |
In continuous distillation, the internal reflux ratio () and the external reflux ratio () are related as |
| A. | = |
| Answer» E. | |
| 47. |
If is the minimum reflux ratio, the optimum reflux ratio may be around __________ . |
| A. | 1.2 to 1.5 |
| B. | 2.5 to 3 |
| C. | 3 to 4 |
| D. | 5 |
| Answer» B. 2.5 to 3 | |
| 48. |
Mass transfer co-efficient varies as , according to the __________ theory. |
| A. | film |
| B. | surface renewal |
| C. | penetration |
| D. | none of these |
| Answer» C. penetration | |
| 49. |
( . ) is termed in mass transfer operation as the __________ number. |
| A. | Stanton |
| B. | Sherwood |
| C. | Peclet |
| D. | none of these |
| Answer» D. none of these | |
| 50. |
Humid volume is the total volume in m of 1 kg of |
| A. | vapour laden gas at 1 atm. and room temperature. |
| B. | gas plus its accompanying vapour at 1 atm. and room temperature. |
| C. | gas plus its accompanying vapour at 1 atm. and gas temperature. |
| D. | vapour laden gas at 1 atm. and gas temperature. |
| Answer» D. vapour laden gas at 1 atm. and gas temperature. | |