Sodium has body centred packing. Distance between two nearest atoms is 3.7 $$\mathop A\limits^ \circ $$. The lattice parameter is
A
4.3 $$\mathop A\limits^ \circ $$
B
3.0 $$\mathop A\limits^ \circ $$
C
8.6 $$\mathop A\limits^ \circ $$
D
6.8 $$\mathop A\limits^ \circ $$
Explanation
Distance between nearest atoms in body
centred cubic lattice (bcc),
d = $${{\sqrt 3 } \over 2}a$$
Given d = 3.7 $$\mathop A\limits^ \circ $$
$$ \therefore $$ $$a = {{3.7 \times 2} \over {\sqrt 3 }}$$ = 4.3 $$\mathop A\limits^ \circ $$
