Solid State - Result Question 33
####33. The empty space in this hcp unit cell is
(a) $74 %$
(b) $47.6 %$
(c) $32 %$
(d) $26 %$
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Answer:
Correct Answer: 33. (d)
Solution:
- Packing fraction $=\frac{\text { Volume occupied by atoms }}{\text { Volume of unit cell }}$
$$ =6 \times \frac{4}{3} \pi r^{3} \times \frac{1}{24 \sqrt{2} r^{3}}=0.74 $$
$\Rightarrow$ Fraction of empty space $=1-0.74=0.26=26 %$
