Lattice Structures $(15$ P$)$

Two different unit cells A and B of typical metallic lattice structures are shown in the

picture below:

A

B

a$)$ What does a "unit cell" generally describe $?(2$ P$)$

b$)$ Which type of unit cell is shown in A resp. B $?(2$ P

c$)$ What is meant by the $$effective number of atoms per unit cell$($EN$)?$ What is

EN for A resp. B $?(3$ P$)$

d$)$ What is the mathematical relation between atomic radius $($r$)$ and edge length

$($a$)$ of above shown unit cell B $?$

e$)$ What is meant by the $$APF$$ of a lattice structure $?$ Briefly explain.

f$)$ Please calculate the APF of structure B

g$)$ The APF of unit cells A and B is equal. What is the structural difference between the two lattice types $?$ Briefly explain