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Unformatted text preview: 6. Total distance traveled by an atom compared to the root mean square distance is a. larger b. smaller c. equal (a ) 7. Arrhenius factor that describes the probability of successful jump of an atom over a barrier with free energy Gm is a. exp(-Gm/kT) b. exp(Gm/kT) c. 1 ( a) 8. Match the following with respect to mechanism of diffusion, a. substitutional atoms vacancy mechanism (a ) b.smaller atoms interstitial mechanism (b ) 9. The units of flux J used in diffusion are a. cm2/sec b. atoms/cm2.sec c.atoms/cm2 (b ) 10. Fick's second law of diffusion is obtained by applying a. conservation of mass b. conservation of energy c. random walk (a ) 11. Bonus question. Oxidation of metals, example rusting of iron and steel in atmosphere, takes place by diffusion of oxygen in an oxide layer. Which of the following equations will describe the thickness of the oxide layer, X formed after time t, a. X= constant. (t) b. X2=constant. (t) c. X=constant. exp(t).(b)...
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- Spring '08