If the cation is present in the tetrahedral void,what is the radius ratio ${r_ + }/{r_ - }$?

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?

Which of the following statements is not true about the $NaCl$ structure?

In sodium chloride,$Cl^-$ ions form a $ccp$ arrangement. In this structure,where are the $Na^+$ ions located?

Total volume of atoms present in a face-centred cubic unit cell of a metal is ($r$ is atomic radius)

The number of unit cells in $58.5 \ g$ of $NaCl$ is nearly