Question

Sodium has body centred packing. Distance between two nearest atoms is $3.7\stackrel{\circ }{A}$. The lattice parameter is

• A. $4.3\stackrel{\circ }{A}$
• B. $3.0\stackrel{\circ }{A}$
• C. $8.6\stackrel{\circ }{A}$
• D. $6.8\stackrel{\circ }{A}$

Answer 1

The correct option is A $4.3\stackrel{\circ }{A}$

Given,

$d=3.7A^0$

$r=\frac{d}{2}$

$r=\frac{3.7}{2}=1.85A^0$

For body centered packing,

radius, $r=\frac{a\sqrt{3}}{4}$

where, $a=$ Lattice parameter

$a=\frac{4r}{\sqrt{3}}$

$a=\frac{4\times 1.85}{\sqrt{3}}{A}^0$

$a=4.3A^0$

The correct option is A.