Question

$CsBr$ crystal has $bcc$ structure. It has an edge length of $4.3Å.$ The shortest interionic distance between $Cs^{+}$ and $Br^{-}$ions is.

• A. $1.86Å$
• B. $3.72Å$
• C. $4.3Å$
• D. $7.44Å$

Answer 1

Answer: (B)

$3.72Å$

Answer 2

Closest approach in bcc lattice

$= \frac{1}{2}$ of body diagonal $= \frac{1}{2} \times \sqrt{3}a$ $= \frac{\sqrt{3}}{2} \times 4.3 = 3.72Å$.