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

Answer 2

$r_{+}/r_{-} = \frac{180}{187} = 0.962$ which lies in the range of $0.732 - 1.000$, hence co-ordination number = 8 i.e. the structure is $CsCl$ type.