Diffusion MCQ Questions and Answers for Practice

1. Diffusion can occur in ....................... materials

1. Solid
2. Liquid
3. Gaseous
4. All

2. Probably the fastest diffusing species in Fe is

1. H
2. Ni
3. W
4. C

3. The value of error function for 8 is

1. -8
2. -1
3. 1
4. 8

4. The value of error function for 0 is

1. -1
2. 1
3. None

5. The following mechanism contributes very little the diffusivity

1. Vacancy
2. Interstitial
3. Substitutional
4. Self-interstitial

6. Not an example for short-circuit path

1. Vacancy
2. Dislocations
3. Grain boundaries
4. External surfaces

7. Example for steady-state diffusion

1. Hydrogen purification by palladium sheet
2. Doping semi-conductors
3. Corrosion resistance of duralumin
4. Decarburization of steel

8. The most influencing factor of diffusivity

1. Diffusing species
2. Temperature
3. Lattice structure
4. Presence of defects

9. The following phenomena are useful in zone-refining process

1. Coring
2. Segregation
3. Both
4. None

10. Macro-segregation can be removed by

1. Annealing
2. Hot working
3. Both
4. None

11. The following enhances the coring

1. Minute difference between liquids and solids
2. Marked difference between liquids and solids
3. Either
4. None