Question

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

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

Answer 1

Answer: (B)

$1:2$

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