Question

The ionic radii of $R{b}^{+}$ and $I^{-}$ are $1.46$ and $2.16\mathring{A}$. The most probable type of structure exhibited by it is

• A. $CsCl$ type
• B. $NaCl$ type
• C. $ZnS$ type
• D. $Ca{F}_2$ type

Answer 1

Answer: (B)

Radius ratio $\frac{r_{R{b}^{+}}}{r_{I^{-}}}=\frac{1.46}{2.16}=0.68$
$\Rightarrow$ Between $0.414$ and $0.732$
Hence rock salt $(NaCl)$ structure.