Question

An ionic compound $AB$ has $ZnS$ type structure, if the radius $A^{+}$ is $22.5pm$, then the ideal radius of $B$ is

• A. 54.35 pm
• B. 100 pm
• C. 145.16 pm
• D. None of these

Answer 1

Answer: (B)

Since ionic compound $AB$ has $ZnS$ type structure, therefore it has tetrahedral holes, for which,
$\frac{\text{ Radius of cation }}{\text{ Radius of anion }}=0.225$
$\frac{r_{+}}{r_{-}}=0.225$
$\frac{22.5}{r_{-}}=0.225$
Hence, $r_{-}=100pm$