A metal crystallizes in a closed packed structure, the atoms stack together occupying maximum space and leaving minimum vacant space. Each sphere in the first layer is in contact with six neighbours. Now while arranging the second layer on the first layer, spheres are placed in depression of first layer. Spheres of third layer lie in the depression of second layer.
This repeating arrangement of atoms produces a giant lattice.
If one of the edge length of unit cell is `'a'` what is the shortest distance between two atoms?

Options

A. `(sqrt(3)a)/4`
B. `a/4` or `a/3`
C. `a` or `a/(sqrt(2))`
D. `a/2`

Answer

C

Explanation

Above packing represent two possible arrangements, hexagonal close packing or cubic close packing, hence ,minimum distance `a` or `a/(sqrt(2))`