MCQOPTIONS
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MCQOPTIONS
This section includes 15 Mcqs, each offering curated multiple-choice questions to sharpen your Phase Transformation knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
During a diffusion process, at time 1s the average atom will have advanced a radial distance r from the origin and it is given by_________ (D = 2.5*10-11 (m2/s)) |
| A. | 48000m |
| B. | 45000m |
| C. | 36000m |
| D. | 24000m |
| Answer» B. 45000m | |
| 2. |
Assume that on average an interstitial atom jumps 6 times per second and that each jump is in a random direction, then the probability of the atom jumping to every one of the six adjacent sites is given by___________ |
| A. | 1/6 |
| B. | 1/3 |
| C. | 1 |
| D. | 1/2 |
| Answer» D. 1/2 | |
| 3. |
After 2s, the average atom has an advanced radial distance of 3m from the origin, then calculate the diffusion coefficient__________ (in m2/s) |
| A. | 0.32 |
| B. | 0.48 |
| C. | 0.69 |
| D. | 0.96 |
| Answer» B. 0.48 | |
| 4. |
For a random walk during a diffusion process, at time t the average atom will have advanced a radial distance r from the origin and it is given by_________ |
| A. | 3.6/ Dt |
| B. | 2.4/ Dt |
| C. | 4.8 Dt |
| D. | 1.2 DT |
| Answer» C. 4.8 Dt | |
| 5. |
State the reason behind the followingThe diffusion coefficient for carbon in fee-Fe at 1000 C is 2.5 X 10-11 (m2*s-1) at 0.15 wt% C, but it rises to 7.7 x 10-11 (m2*s-1) in solutions containing 1.4 wt % C. |
| A. | Melting point of carbon |
| B. | C atom strain Fe lattice |
| C. | Melting point of Fe atom |
| D. | Shrinking of C atom |
| Answer» C. Melting point of Fe atom | |
| 6. |
The mean vibrational energy of a particle is given by 1.656*10-20. Calculate the temperature at which the particle attains this vibrational energy? |
| A. | 900K |
| B. | 400K |
| C. | 300K |
| D. | 500K |
| Answer» C. 300K | |
| 7. |
The diffusion coefficient is given as 16(m2/s) and the concentration gradient is given as 2(mol/m^4), the flux of the particle is given by _____ |
| A. | 8 |
| B. | 32 |
| C. | -32 |
| D. | -8 |
| Answer» D. -8 | |
| 8. |
The distance between two adjacent atoms in an octahedral site is given by _____ (if the sides of the unit cell are of length a, FCC material) |
| A. | a/ 2 |
| B. | a/2 |
| C. | 3a/ 2 |
| D. | 2a |
| Answer» B. a/2 | |
| 9. |
Usually the concentration of interstitial atoms is_________ |
| A. | So low that only a fraction of available site is occupied |
| B. | Very high that entire fraction is occupied |
| C. | Low but most of the fraction of available site is occupied |
| D. | High but most of the available sites are vacant |
| Answer» B. Very high that entire fraction is occupied | |
| 10. |
The movement of atom from copper to Nickel is an example of________ |
| A. | Intra diffusion |
| B. | Inter diffusion |
| C. | Self diffusion |
| D. | Mixed diffusion |
| Answer» C. Self diffusion | |
| 11. |
Fick s first law can be directly applied only in a steady-state condition, where the composition does not change with time. |
| A. | True |
| B. | False |
| Answer» C. | |
| 12. |
When considering the flux of particles (atoms, molecules, ions etc.) in a one-dimensional system caused by a concentration gradient, the flux can be expressed as ____________ |
| A. | J = dm/dt |
| B. | J = dm/(dt*A) |
| C. | J = dm/dx |
| D. | J = dm/(dx*A) |
| Answer» C. J = dm/dx | |
| 13. |
Vibrational energy is increased by increasing the amplitude of the oscillations. |
| A. | True |
| B. | False |
| Answer» D. | |
| 14. |
Which of the following atoms use the vacancy mechanism to diffuse? |
| A. | Large atoms |
| B. | Surface atoms |
| C. | Substitutional atoms |
| D. | Small interstitial atoms |
| Answer» D. Small interstitial atoms | |
| 15. |
The mean vibrational energy possessed by each atom at 300K is given by__________ (In joules) |
| A. | 4.14*10<sup>-23</sup> |
| B. | 1.242*10<sup>-20</sup> |
| C. | 1.242*10<sup>-23</sup> |
| D. | 1.242*10<sup>-21</sup> |
| Answer» C. 1.242*10<sup>-23</sup> | |