**Hexagonal close-packed (hcp)** structure has coordination number:
A6
B8
C10
D12
Answer & Solution
Correct answer: D. 12
Like fcc, hcp has CN = 12. (Both fcc and hcp are 'closest-packed' with the maximum possible packing efficiency of 74%.) Examples: Zn, Mg, Cd (hcp); Cu, Au, Ag (fcc).
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