Question

The coordination number of cation and anion in $Ca{F}_2$ and $CsCl$ are, respectively :

• A. $8:4$ and $6:3$
• B. $6:3$ and $4:4$
• C. $8:4$ and $8:8$
• D. $4:2$ and $2:4$

Answer 1

The correct option is C $8:4$ and $8:8$

In $Ca{F}_2$, cations are present at ccp sites and anions are present at tetrahedral voids, and coordination number of cations and anions in $Ca{F}_2$ are 8 and 4 respectively.
In $CsCl$, cations are present at corners of cubes and anions are present at the central cubic void, and coordination number of cations and anions in $CsCl$ are 8 and 8 respectively.