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?

The radius of divalent cation $A^{+2}$ is $94 \, pm$ and divalent anion $B^{-2}$ is $146 \, pm$. The structure of compound $AB$ is

Consider an ionic solid $MX$ with $NaCl$ structure. Create a new unit cell $(Z)$ from the unit cell of $MX$ by following the sequential instructions given below. Ignore charge balance.
$(i)$ Remove all anions $(X)$ except the central one.
$(ii)$ Replace all face-centered cations $(M)$ with anions $(X)$.
$(iii)$ Remove all cations $(M)$ at the corners.
$(iv)$ Replace the central anion $(X)$ with a cation $(M)$.
The value of $\left(\frac{\text{number of anions}}{\text{number of cations}}\right)$ in $Z$ is . . . . .

Copper crystallizes in $f.c.c.$ with a unit cell length of $361 \ pm$. What is the radius of copper atom? (in $pm$)

What is the limiting radius ratio for a tetrahedral shape?

Coordination numbers of $Zn^{2+}$ and $S^{2-}$ in the crystal structure of wurtzite are