What is the coordination number of any particle in the $fcc$ (face-centered cubic) crystal lattice?

The ratio of anion radius to cation radius of a crystal is $10 : 9.3$. Then, the coordination number of the cation in the crystal is

If the distance between $Na^{+}$ and $Cl^{-}$ ions in sodium chloride crystal is $X \ pm$, the length of the edge of the unit cell is

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

In an ionic crystal,$\frac{r^{+}}{r^{-}} = 0.524$,the coordination number of the cation is:

The compound $AB$ crystallizes in a cubic lattice in which both $A$ and $B$ atoms have coordination numbers of $8$. To what crystal class does the unit cell belong?