MCQOPTIONS
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MCQOPTIONS
This section includes 7 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<sup>-12</sup> |
| B. | 5.91*10<sup>-10</sup> |
| C. | 5.91*10<sup>-11</sup> |
| D. | 5.91*10<sup>-13</sup> |
| Answer» B. 5.91*10<sup>-10</sup> | |
| 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. |
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<sup>-12</sup> |
| B. | 9.87*10<sup>-13</sup> |
| C. | 9.87*10<sup>-11</sup> |
| D. | 9.87*10<sup>-10</sup> |
| Answer» B. 9.87*10<sup>-13</sup> | |
| 5. |
For a component A of a mixture, concentration as a function of x is given:
|
| A. | nCalculate 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<sup>-5</sup>m<sup>2</sup>/s. |
| B. | 0.2567 |
| C. | 2.567 |
| D. | 0.0025 |
| E. | 3.541 |
| Answer» B. 0.2567 | |
| 6. |
A reaction 3A+2B+C=1.5D+E occurs in a reactor at steady state. What will be the value of the flux ratio NA/ND
|
| A. | -0.5 |
| B. | 2 |
| C. | -0.5 |
| Answer» B. 2 | |
| 7. |
In the expression for molar flux NA=(NA+NB)CA/C DABdCA/dz, the terms representing bulk flow and molecular diffusion are, respectively |
| A. | (N<sub>A</sub>+N<sub>B</sub>)C<sub>A</sub>/C, D<sub>AB</sub>dC<sub>A</sub>/dz |
| B. | (N<sub>A</sub>+N<sub>B</sub>)C<sub>A</sub>/C, D<sub>AB</sub>dC<sub>A</sub>/dz |
| C. | (N<sub>A</sub>+N<sub>B</sub>)C<sub>A</sub>/C, (N<sub>A</sub>+N<sub>B</sub>)C<sub>A</sub>/C |
| D. | (D<sub>AB</sub>dC<sub>A</sub>/dz, D<sub>AB</sub>dC<sub>A</sub>/dz) |
| Answer» B. (N<sub>A</sub>+N<sub>B</sub>)C<sub>A</sub>/C, D<sub>AB</sub>dC<sub>A</sub>/dz | |