Question

In calcium, fluoride having the florite structures. The coordination number for calcium ion `(Ca^(2+))` and fluoride ion `(F^(-))` are
A. `4` and `2`
B. `6` and `6`
C. `8` and `4`
D. `4` and `8`

Answer 1

Correct Answer - 3
The `Ca^(2+)` ions are located at the face centred cubic lattice points and therefore have cubic closest packed arrangement .the `F^(-)` ions occupy all the eight tetrahedral voids.Thus the coordination number of `Ca^(2+)` ion (surrounded by eight tetrahedral voids ) is eight while the coordination number of `F^(-)` ion (occupying tetrahedral void) is four.