A Sample of Co Crystallizes in the Hexagonal Closest-Packed (Hcp)

Multiple Choice

A sample of Co crystallizes in the hexagonal closest-packed (hcp) structure. Each atom in a layer is surrounded by and touches 6 other Co atoms. If the distance between Co atom centers within each layer is 2.0 × 10² pm, what is the distance between centers of nearest neighbors in adjacent layers?

A) 1.5 × 10² pm
B) 4.0 × 10² pm
C) 2.3 × 10² pm
D) 2.0 × 10² pm
E) none of these