MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 9 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 industries titanium is hardened through diffusion of carbon. The concentration of carbon at 1mm into the surface of the titanium slab is 0.25kg/m3 and at 3mm the concentration is 0.68kg/m3. The rate at which the carbon is entering into its surface is 1.27*10-9kg/m2.s. calculate the value of diffusion coefficient of carbon. |
| A. | 5.91*10-12 |
| B. | 5.91*10-10 |
| C. | 5.91*10-11 |
| D. | 5.91*10-13 |
| Answer» B. 5.91*10-10 | |
| 2. |
The gas A diffuses through non-diffusing B from point 1 to point 2. The total pressure is 2atm and yA1=0.1 and yA2=0.Then the ratio (dPA/dz)1/(dPA/dz)2 is |
| A. | 10 |
| B. | 1.11 |
| C. | 0.9 |
| D. | 2.3 |
| Answer» D. 2.3 | |
| 3. |
Which among the following is the statement of the ‘Fick’s Law’? |
| A. | The molar flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species. |
| B. | The mass flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species. |
| C. | The molar flux of species relative to an observer moving with the mass average velocity is proportional to the concentration gradient of the species. |
| D. | The molar flux of species relative to a stationary observer is proportional to the concentration gradient of the species. |
| Answer» B. The mass flux of species relative to an observer moving with the molar average velocity is proportional to the concentration gradient of the species. | |
| 4. |
At which condition molar flux with respect to a stationary observer and with respect to an observer moving with molar average velocity? |
| A. | In a very dilute solution |
| B. | In a highly concentrated solution |
| C. | At moderate concentration |
| D. | Never |
| Answer» B. In a highly concentrated solution | |
| 5. |
A sheet of Fe 1.0 mm thick is exposed to an oxidizing gas on one side and a deoxidizing gas on the other at 725°C. After reaching steady state, the Fe membrane is exposed to room temperature, and the C concentrations at each side of the membrane are 0.012 and 0.075 wt%. Calculate the diffusion coefficient (m2/sec) if the diffusion flux is 1.4×10-8kg/m2-sec. |
| A. | 9.87*10-12 |
| B. | 9.87*10-13 |
| C. | if the diffusion flux is 1.4×10-8kg/m2-sec.a) 9.87*10-12b) 9.87*10-13c) 9.87*10-11 |
| D. | 9.87*10-10 |
| Answer» B. 9.87*10-13 | |
| 6. |
For a component A of a mixture, concentration as a function of x is given:CA=5e-10x (x is in cm and CA in mol/liter)Calculate the value of diffusion velocity (m/s)of the component A at the point x=0, if diffusivity of A in the mixture is 2.567*10-5m2/s. |
| A. | 0.2567 |
| B. | 2.567 |
| C. | 0.0025 |
| D. | 3.541 |
| Answer» B. 2.567 | |
| 7. |
Consider loss of ethanol vapor by diffusion from a half-filled open test tube. At what point in the diffusion path will the contribution of the bulk flow term to the molar flux be maximum? |
| A. | At the liquid-gas interface |
| B. | In the bulk liquid |
| C. | In the bulk gas |
| D. | None of the mentioned |
| Answer» B. In the bulk liquid | |
| 8. |
In the expression for molar flux NA=(NA+NB)CA/C – DABdCA/dz, the terms representing bulk flow and molecular diffusion are, respectively |
| A. | (NA+NB)CA/C, DABdCA/dz |
| B. | (NA+NB)CA/C, DABdCA/dz |
| C. | (NA+NB)CA/C, (NA+NB)CA/C |
| D. | (DABdCA/dz, DABdCA/dz) |
| Answer» B. (NA+NB)CA/C, DABdCA/dz | |
| 9. |
For what kind of mixtures DAB=DBA holds? |
| A. | Ideal |
| B. | Real |
| C. | For both real and ideal |
| D. | This relation is never true. |
| Answer» B. Real | |