Question

In $A^{+}{B}^{-}$ ionic compound, radii of $A^{+}$ and $B^{-}$ ions are $180pm$ and $187pm$ respectively. The crystal structure of this compound will be:

• A. $NaCl$ type
• B. $CsCl$ type
• C. $Zns$ type
• D. Similar to diamond

Answer 1

Answer: (B)

$CsCl$ type

$r_{+}/r_{-}=\frac{180}{187}=0.962$

It lies in the range of $0.732-1.000$, hence co-ordination number $=8$ i.e. the structure is $CsCl$ type.