Properties Of Solids

Answer:

6

Explanation:

The coordination number of an ion in a crystal lattice is determined by the ratio of the radii of the cation and anion. The formula to determine the coordination number is given by the radius ratio rule, which relates the ionic radii of the cation and anion in an ionic compound:

The radius ratio is calculated as:

According to the radius ratio rule, for a ratio between 0.414 and 0.732, the coordination number is typically 6. Therefore, the coordination number for both the and ions in the compound AB is 6.