How much part of an atom occupies each corner of a $bcc$ unit cell?

In an $FCC$ unit cell,a cube is formed by joining the centers of all the tetrahedral voids to generate a new cube. Then the new cube would contain effective voids as

In the spinel structure,oxide ions are cubical-closest packed where $1/8$ of tetrahedral voids are occupied by $A^{2+}$ cations and $1/2$ of octahedral voids are occupied by $B^{3+}$ cations. The general formula of the compound having spinel structure is

The packing efficiency of the two-dimensional square unit cell shown below is (in $\%$)

In a crystal lattice,the number of octahedral voids compared to tetrahedral voids is ...............

The anions $(A)$ of a $C_{p}A_{q}$ molecule form an $fcc$ lattice. Cations $(C)$ are positioned at the body center and half of the edge centers. The formula of the molecule is: