Question

Sodium metal crystallizes in body centred cubic lattice with edge length of $4.29 \,\mathring{A}$. The radius of sodium atom is

• A. $2.857 \,\mathring{A}$
• B. $1.601 \,\mathring{A}$
• C. $2.145 \,\mathring{A}$
• D. $1.857 \,\mathring{A}$

Answer 1

Answer: (D)

In body centred cubic unit cell (bcc) (sphere along the body diagonal )

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

where, $ r=$ radius of sphere

a= edge length

$a=4.29\,\mathring{A}$

$ \Rightarrow r=\frac{\sqrt{3}}{4} \times 4.29$

$=1.857\,\mathring{A}$