Question

The number of atoms in his hcp unit cell is:

• A. $4$
• B. $6$
• C. $12$
• D. $17$

Answer 1

Answer: (B)

$6$

$Z_{effective}$ of $HCP$ unit cell= $12\times \frac{1}{6}$ (Body Corners)

$+2\times \frac{1}{2}$ (Face Centers)

$+3$ (Completely present inside)

$Z_{effective}=2+1+3=6$ number of atoms.