Question

In crystalline solid of $Na$ which crystallises in $FCC$, distance between two nearest $N{a}^{+}$ (if edge length is a)

• A. $\frac{a}{\sqrt{2}}$
• B. $\frac{a}{\sqrt{3}}$
• C. $\frac{a}{2}$
• D. $2a$

Answer 1

The correct option is A $\frac{a}{\sqrt{2}}$

Distance between two edge centres
$=\sqrt{{\left(\frac{a}{2}\right)}^2+{\left(\frac{a}{2}\right)}^2}$
$=\frac{a}{\sqrt{2}}$