For which ionic compound is the radius ratio $0.93$?

If the radius ratio for an ionic solid is $0.5248$ and the radius of the cation is $0.95 \ \mathring{A}$,what is the radius of the anion?

The coordination number of a sphere in a face-centered cubic $(fcc)$ lattice is .....

In a mineral $MX_2$,$M^{+2}$ ions are arranged in a $ccp$ structure and $X^{-}$ ions occupy the tetrahedral voids. What are the number of cations and anions per unit cell,the coordination number of the cation,and the percentage of occupied tetrahedral voids,respectively?

For a tetrahedral structure,the limiting radius ratio $r_c^+ / r_a^-$ is .......

An element has a $bcc$ structure with $12.08 \times 10^{23}$ unit cells. What is the total number of atoms in these unit cells?