Question

$CsCl$ crystallises in body centred cubic lattice. If $‘a^{\prime }$ is its edge length, then which of the following expressions is correct?

• A. $r_{C{s}^{+}}+r_{C{l}^{-}}=3a$
• B. $r_{C{s}^{+}}+r_{C{l}^{-}}=\frac{3a}{2}$
• C. $r_{C{s}^{+}}+r_{C{l}^{-}}=\frac{\sqrt{3}a}{2}$
• D. $r_{C{s}^{+}}+r_{C{l}^{-}}=\sqrt{3}a$

Answer 1

Answer: (C)

$r_{C{s}^{+}}+r_{C{l}^{-}}=\frac{\sqrt{3}a}{2}$

Correct option is $C$.

Cesium and chloride ion touches each other along body diagonal. Half of the body diagonal is the sum of their ionic radii.