Calcium fluoride, having the fluorite structure, the coordination number for calcium ion (Ca²⁺) and fluoride ion (F⁻) are:
A. 8 and 4
B. 4 and 8
C. 4 and 2
D. 6 and 6

In the fluorite structure, also known as the face-centered cubic (FCC) structure, each ion is surrounded by a certain number of neighboring ions. The coordination number for each ion in calcium fluoride (CaF2) is as follows:

The coordination number for the calcium ion (Ca²⁺) is 8. This means that each calcium ion is surrounded by 8 fluoride ions.

The coordination number for the fluoride ion (F⁻) is 4. This means that each fluoride ion is surrounded by 4 calcium ions.

So, the correct answer is:

A. 8 and 4