Question

The coordination number of each sphere in hcp arrangement is ______.

Options

• 8

• 12

• 6

• 4

Answer 1

The coordination number of each sphere in hcp arrangement is 12.

Explanation:

In the hcp (hexagonal close packing) arrangement, each sphere is in contact with 12 other spheres, giving it a coordination number of 12.
This includes 6 neighbours in the same layer, 3 in the layer above, and 3 in the layer below.