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

In a solid $AB$ having the $NaCl$ structure,$A$ atoms occupy the corners of the cubic unit cell. If all the face-centered atoms along one of the axes are removed,then the resultant stoichiometry of the solid is

The mineral $ZnAl_2O_4$ has a spinel structure. The percentage of occupied octahedral voids is ........... $\%$.

Find the radius of an atom in $fcc$ unit cell having edge length $393 \ pm$. (in $pm$)

If three elements $A, B, C$ crystallize in a cubic solid lattice with $B$ atoms at the cubic centers, $C$ atoms at the center of edges, and $A$ atoms at the corners, then the formula of the compound is

The ionic radii of $A^{+}$ and $B^{-}$ ions are $0.98 \times 10^{-10} \ m$ and $1.81 \times 10^{-10} \ m$. The coordination number of each ion in $AB$ is.......