In the $NaCl$ crystal structure,how many chloride ions surround each sodium ion?

In an ionic compound,the unit cell has $A$ ions at the corners and $B$ ions at the face centers. What is the empirical formula of the compound?

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?

If the length of the body diagonal of a cube is $x$,then the tetrahedral void will be at a distance of ....... from the center of the cube.

In a $ccp$ lattice of $X$ and $Y$,$X$ atoms are present at the corners while $Y$ atoms are at face centers. What would be the formula of the compound if one of the $X$ atoms from a corner is replaced by a $Z$ atom?

In an $AgI$ crystal,$I^{-}$ ions form a close-packed structure. What percentage of the tetrahedral voids is occupied by $Ag^{+}$ ions?