Question

Solid $A^{+}{B}^{-}$ has a bcc structure. It the distance of closest approach between two atoms is $173pm$, the edge length of the cell is:

• A. $200pm$
• B. $\frac{\sqrt{3}}{\sqrt{2}}pm$
• C. $142.2pm$
• D. $\sqrt{2}pm$

Answer 1

The correct option is A $200pm$

As we know for a BCC structure

$d=\frac{\sqrt{3}a}{2}$

$\Rightarrow a=\frac{2d}{\sqrt{3}}$

$=\frac{2\times 173}{1.732}$

$=200pm$