How many formula units are there in the unit cell of sodium chloride $(NaCl)$?

An element has a face-centred cubic $(fcc)$ structure with a cell edge of $a$. The distance between the centres of two nearest tetrahedral voids in the lattice is

What is the coordination number of sodium in $Na_2O$?

An ionic compound has a unit cell consisting of $A$ ions at the corners of a cube and $B$ ions on the centres of the faces of the cube. The empirical formula for this compound would be

In $F.C.C.$,each face of the unit cell is shared equally by how many unit cells?

Coordination number of $Zn^{2+}$ in $ZnS$ (zinc blende) is