In a structure of mixed oxide,oxide ions are in $CCP$. One-fifth of tetrahedral voids are occupied by divalent ion $(A^{2+})$ while half of the octahedral voids are occupied by trivalent ion $(B^{3+})$. The formula of the oxide is:

Find the void volume of a $bcc$ unit cell in $cm^3$ if the volume of the unit cell is $1.5 \times 10^{-22} \ cm^3$.

The structure of a mixed oxide is cubic close packed $(ccp)$. The cubic unit cell of the mixed oxide is composed of oxide ions. One-fourth of the tetrahedral voids are occupied by divalent metal $A$ and the octahedral voids are occupied by a monovalent metal $B$. The formula of the oxide is:

$A$ compound is formed by two elements $A$ and $B$. Atoms of the element $B$ (as anion) make $ccp$ lattice and those of element $A$ (as cation) occupy all tetrahedral voids. The formula of the compound is

$A$ solid has an $hcp$ lattice. Atoms of $Z$ (anions) form the $hcp$ lattice. Atoms of $X$ (cations) occupy all the octahedral voids in the lattice. Atoms of $Y$ (cations) occupy half of the tetrahedral voids. What is the molecular formula of the solid?

$A$ compound is formed by cation $C$ and anion $A$. The anions form hexagonal close packed $(hcp)$ lattice and the cations occupy $75 \%$ of octahedral voids. The formula of the compound is