Question

Sodium metal crystallises in body centred cubic lattice with cell edge $427$ pm. Thus, radius of sodium atom is

• A. $429$ pm
• B. $214.5$ pm
• C. $186$ pm
• D. $185$ pm

Answer 1

Answer: (D)

In $bcc$ structure, radius $(r)$ is related to edge length by
$r=\frac{\sqrt{3}}{4}a$
$=\frac{\sqrt{3}}{4}\times 427pm$
$=185.67$
$=185pm$