1 According to Fick's first law: A. Diffusion flux is proportional to the concentration gradient B. Diffusion flux is not proportional to the concentration gradient C. The flux is time dependent D. None of the above 2 Which statement is true for steady-state diffusion: A. The concentration gradient is the slope of the concentration profile curve at some specific point B. The driving force is the concentration gradient. C. The flux is time independent. D. All of the above 3 For unsteady-state diffusion: A. There is a net accumulation or depletion of diffusing species B. The flux is time dependent C. Both of the above D. None of the above 4 The magnitude of the diffusion coefficient: A. is indicative of the rate of atomic motion B. depends on both host and diffusing species C. depends on temperature D. all of the above 5 For diffusion, a small activation energy results in: A. a relatively large diffusion coefficient B. a relatively small diffusion coefficient C. all of the above D. none of the above 6 The activation energy and diffusion coefficient for the diffusion of zinc in copper at 650C are 189000 J/mol and 4.8 x 10-16 m/s, respectively. If temperature is increased to 850C: A. the diffusion coefficient will decrease B. the activation energy will remain unchanged C. the activation energy will increase D. None of the above 7 Which statement is true for vacancy diffusion: A. It occurs via the exchange of an atom residing on a normal lattice site with an adjacent vacancy B. An atom migrates from one interstitial site to an adjacent one. C. Both of the above. D. None of the above. df Cudf