Question

The empty space in this hcp unit cell is :

• A. $74\%$
• B. $48.6\%$
• C. $32\%$
• D. $26\%$

Answer 1

The correct option is D $26\%$

Contents	BCC	CCP/FCC	HCP
Type of packing but not close packing	ABAB........... close packing	ABCABC....... close packing	ABAB
No. of atoms	2	4	6
Co-ordination no.	8	12	12
Packing efficiency	68%	74%	74%

The packing efficiency of hcp cell is 74% so the empty space is 26%

Hence, the correct option is $\text{D}$