$3.$ Characterization of materials involves:

a$)$ Determining their chemical composition

b$)$ Analyzing their physical properties

c$)$ Studying their microstructure

d$)$ All of the above

Diffusivity is affected by:

a$)$ Temperature

b$)$ Composition

c$)$ Presence of defects

d$)$ All of the above

Activation energy is the:

a$)$ Energy required for diffusion to occur

b$)$ Energy released during di