Q8 / 150 · MHT CET 2021 (21 Sep Shift 1) · Chemistry
What is the percentage efficiency of packing in BCC structure?
- A$32 \%$
- B$74 \%$
- C$26 \%$
- Correct answerD$68 \%$
Solution
Packing efficiency:
$$
\begin{aligned}
& \text { P.E. }=\frac{\mathrm{z} \times \frac{4}{3} \pi \mathrm{r}^3}{V}=\frac{2 \times \frac{4}{3} \times \pi\left(\frac{\sqrt{3} \mathrm{a}}{4}\right)^3}{\mathrm{a}^3}=\frac{\sqrt{3} \mathrm{a}}{8}=0.68 \\
& {\left[\because \mathrm{z}=2, \mathrm{r}=\frac{\sqrt{3} \mathrm{a}}{4}, V=\mathrm{a}^3\right]}
\end{aligned}
$$
In B.C.C., $68 \%$ of total volume is occupied by atoms or ions.
Hence, the correct answer is option: 'D'.