Question

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

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

Answer 1

The correct option is B $NaCl$ type

According to the problem:

$\frac{{\gamma }^{+}}{{\gamma }^{-}}=\frac{1.46}{2.16}=0.67$

Thus, it lies in range of 0.$414$ to $0.732$

Thus,

coordination umber=$6$

Implies that $NaCl$ type