Multiple Choice

What are the correct answers to these multiple choice questions?

Secondary or Van der Waals force is:

a$.$ Attraction between two dipoles

b$.$ Attraction between two ions

c$.$ Attraction between two metal atoms

d$.$ Attraction between two carbon atoms

A single crystal

a$.$ Consist of closed packed atoms

b$.$ Consist of the same unit cell repeated in all three directions

c$.$ Consist of the same unit cell but repeated irregularly

d$.$ Consists of randomly distributed atoms

The number of vacancies in a material depends on

a$.$ Other Defects

b$.$ Electric Field

c$.$ Magnetic Field

d$.$ Temperature

Dislocations

a$.$ Are one dimensional defects

b$.$ Are characterized by the Burgers vector

c$.$ Cause lattice distortions

d$.$ All of the above

What is the slowest diffusion process?

a$.$ Vacancy assisted diffusion

b$.$ Substitutional atom assisted diffusion

c$.$ Interstitial diffusion

d$.$ None of the above

What is the important law for case hardening $($non$-$steady state diffusion$)$

a$.$ Fick's First Law

b$.$ Fick's Second Law

c$.$ Fick's Third Law

d$.$ All of the above