Question

The ratio of the number of atoms to tetrahedral holes in a unit cell with cubic close packing is:

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

Answer 1

The correct option is B

1 : 2

In ccp lattice, the number of atoms are

$=8\times \frac{1}{8}+6\times \frac{1}{2}=4$

There are a total of 8 tetrahedral voids and 4 octahedral voids in this.

Thus, ratio =4 : 8 :: 1 : 2