Question

The ratio of close-packed atoms to tetrahedral holes in cubic close packing is

• A. $1:1$
• B. $1:3$
• C. $1:2$
• D. $2:1$

Answer 1

Answer: (C)

Every constituent has two tetrahedral voids. In ccp lattice atoms
$=8\times \frac{1}{8}+6\times \frac{1}{2}=4$
$\therefore$ Tetrahedral void $=4\times 2=8$,
Thus, ratio $=4:8::1:2$.