Sodium has body centred packing. Distance between two nearest atoms is $3.7 Å$. The lattice parameter is :

Sodium has body centred packing. Distance between two nearest atoms is $3.7 Å$. The lattice parameter is :
  1. $8.6 Å$
  2. $6.8 Å$
  3. $4.3 Å$
  4. $3.0 Å$

Solution

$\begin{aligned} \frac{\sqrt{3} \mathbf{a}}{2} & =3.7 Å \\ \Rightarrow \quad \mathbf{a} & =\frac{2 \times 3.7}{\sqrt{3}}=4.3 Å \end{aligned}$

Asked in: NEET 2009 (Mains)

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