In calcium fluoride,having the fluorite structure,the coordination numbers for calcium ion $(Ca^{2+})$ and fluoride ion $(F^{-})$ are

$Xe$ crystallizes in an $fcc$ structure. If the edge length of the unit cell of $Xe$ is $620 \, pm$, then the distance between two nearest $Xe$ atoms is .............. $pm$.

In a cubic structure of a compound made from $X$ and $Y$,where $X$ atoms are at the corners of the cube and $Y$ atoms are at the face centers of the cube,the molecular formula of the compound is:

In the zinc blende structure,zinc atoms fill up:

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

The number of octahedral voids in a $BCC$ structure is: