Question

The coordination number of each sphere in $\left(HCP\right)$ arragement is:

• A. $8$
• B. $12$
• C. $6$
• D. $10$

Answer 1

The correct option is B $12$

The coordination number of each sphere in $\left(HCP\right)$ arrangement is $12$. Each sphere is surrounded by six spheres in the plane, 3 spheres below the plane and 3 spheres above the plane.