MCQOPTIONS
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MCQOPTIONS
This section includes 12 Mcqs, each offering curated multiple-choice questions to sharpen your Mass Transfer knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In the previous question if the floor has micro pores and water penetrates the floor at a constant rate of 0.1kg/m2h, what will be the time required for the water layer to disappear? |
| A. | 3.64h |
| B. | 4.73h |
| C. | 5.94h |
| D. | 2.36h |
| Answer» B. 4.73h | |
| 2. |
In an accident a container containing ethanol(s.g 0.789) falls down in a room of dimension 1*1*2(all in m). Ethanol forms a layer of 2mm. Ethanol vaporizes and diffuses through a stagnant film of air of thickness 2.5mm. What will be the time required for the water layer to disappear completely. The diffusivity of ethanol in air is 2.567*10-5 m2/s. the total pressure is 1.013 bar and the pressure of ethanol in bulk air is 0.02244 bar and at the ethanol-air interface is 0.02718bar. The temperature is 25.2°C. |
| A. | 4.73h |
| B. | 14.6h |
| C. | 5.87h |
| D. | 16.2h |
| Answer» B. 14.6h | |
| 3. |
In order to prepare Lithium nitride, air is passed gently over a reactor. Suppose that Nitrogen diffuse to a length 5cm before getting reacted with Lithium. Nitrogen reacts with lithium quickly so that partial pressure of Nitrogen at that point is 0. Reactor is a cylinder of length 10cm and diameter 2cm. Assume air to be a mixture of Nitrogen and Oxygen only. The temperature is 298K and total pressure 1atm. Diffusivity of N2 in O2 is 2*10-5m2/s. Calculate the Molar flux (mol/m2.s) of N2 at a distance of 2.5cm from the top with respect to an observer moving with twice the mass average velocity a direction towards the liquid surface. (R=8.205*10-5m3atmK-1mol-1). Assume z=0 at the top of the reactor. |
| A. | 4.242*10-4 |
| B. | 4.242*10-5 |
| C. | 4.242*10-3 |
| D. | 4.242*10-2 |
| Answer» B. 4.242*10-5 | |
| 4. |
Oxygen diffuses through a stagnant layer of air, 1mm thick, ambient temperature 28°C and 1atm total pressure. The partial pressure of oxygen on two sides of layer is P1=0.9atm and P2=0.1atm respectively. Calculate the value of Molar flux (in mol/m2.s) with respect to an observer moving with molar average velocity. Calculate this value at the end of the path where P2=0.1atm. Use R=8.205*10-5m3atmK-1mol-1. |
| A. | 2.713 |
| B. | 1.713 |
| C. | 0.1713 |
| D. | 0.01713 |
| Answer» C. 0.1713 | |
| 5. |
For a gas mixture (A+B) equimolar counterdiffusion takes place. Which among the following statements are correct for molar flux? |
| A. | If temperature is doubled, the flux will get halved |
| B. | If diffusion length is halved, the flux will get halved |
| C. | If temperature is halved, the flux will get halved |
| D. | If temperature is doubled and length is halved, the flux will become four times |
| Answer» B. If diffusion length is halved, the flux will get halved | |
| 6. |
A cylinder of sulfur is kept in a large volume of stagnant air for sublimation. How much time will be required for its complete sublimation? |
| A. | One fourth the time required by sphere of same mass |
| B. | Half the time required by a cube of same mass |
| C. | One fourth the time required by a cube of same mass |
| D. | Infinite |
| Answer» E. | |
| 7. |
The molar average velocity of the components in a binary mixture in which they are in equimolar counter diffusion is |
| A. | Equal to mass average velocity |
| B. | Zero |
| C. | Always negative |
| D. | Always positive |
| Answer» C. Always negative | |
| 8. |
In the previous question if the floor has micro pores and water penetrates the floor at a constant rate of 0.1kg/m2h, what will be the time required for the water layer to disappear? |
| A. | 3.64h |
| B. | 4.73h |
| C. | 5.94h |
| D. | 2.36h |
| Answer» B. 4.73h | |
| 9. |
In an accident a container containing ethanol(s.g 0.789) falls down in a room of dimension 1*1*2(all in m). Ethanol forms a layer of 2mm. Ethanol vaporizes and diffuses through a stagnant film of air of thickness 2.5mm. What will be the time required for the water layer to disappear completely. The diffusivity of ethanol in air is 2.567*10-5 m2/s. the total pressure is 1.013 bar and the pressure of ethanol in bulk air is 0.02244 bar and at the ethanol-air interface is 0.02718bar. The temperature is 25.2°C.$ |
| A. | 4.73h |
| B. | 14.6h |
| C. | 5.87h |
| D. | 16.2h |
| Answer» B. 14.6h | |
| 10. |
A binary liquid mixture is separated by distillation process. The more volatile A vaporizes while less volatile B gets transported in opposite direction. Latent heat of vaporization of A and B is 0.5unit and 1unit respectively. What will be the relation between molar flux of A and B |
| A. | N<sub>A</sub>=2N<sub>B</sub> |
| B. | 2N<sub>A</sub>=N<sub>B</sub> |
| C. | N<sub>A</sub>=4N<sub>B</sub> |
| D. | 4N<sub>A</sub>=N<sub>B</sub> |
| Answer» B. 2N<sub>A</sub>=N<sub>B</sub> | |
| 11. |
In order to prepare Lithium nitride, air is passed gently over a reactor. Suppose that Nitrogen diffuse to a length 5cm before getting reacted with Lithium. Nitrogen reacts with lithium quickly so that partial pressure of Nitrogen at that point is 0. Reactor is a cylinder of length 10cm and diameter 2cm. Assume air to be a mixture of Nitrogen and Oxygen only. The temperature is 298K and total pressure 1atm. Diffusivity of N2 in O2 is 2*10-5m2/s. Calculate the Molar flux (mol/m2.s) of N2 at a distance of 2.5cm from the top with respect to an observer moving with twice the mass average velocity a direction towards the liquid surface. (R=8.205*10-5m3atmK-1mol-1). Assume z=0 at the top of the reactor. |
| A. | 4.242*10<sup>-4</sup> |
| B. | 4.242*10<sup>-5</sup> |
| C. | 4.242*10<sup>-3</sup> |
| D. | 4.242*10<sup>-2</sup> |
| Answer» B. 4.242*10<sup>-5</sup> | |
| 12. |
Oxygen diffuses through a stagnant layer of air, 1mm thick, ambient temperature 28°C and 1atm total pressure. The partial pressure of oxygen on two sides of layer is P1=0.9atm and P2=0.1atm respectively. Calculate the value of Molar flux (in mol/m2.s) with respect to an observer moving with molar average velocity. Calculate this value at the end of the path where P2=0.1atm. Use R=8.205*10-5m3atmK-1mol-1. |
| A. | 2.713 |
| B. | 1.713 |
| C. | 0.1713 |
| D. | 0.01713 |
| Answer» C. 0.1713 | |