In a metal oxide,$O^{2-}$ ions are arranged in $hcp$ lattice while metal ions occupy $2/3$ of the octahedral voids. The simplest 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

Calculate the total volume occupied by all particles in an $fcc$ unit cell if the volume of the unit cell is $6.4 \times 10^{-23} \ cm^3$.

In a face-centred cubic lattice,atom $A$ occupies the corner positions and atom $B$ occupies the face-centred positions. If one atom of $B$ is missing from one of the face-centred points,the formula of the compound is

In a crystal lattice,$C$ anions form a cubic close-packed $(CCP)$ structure. Cations $(A)$ occupy $50\%$ of the tetrahedral voids and cations $(B)$ occupy $50\%$ of the octahedral voids. Determine the molecular formula of the compound.

In a $ccp$ structure of $X$ atoms,$Y$ atoms occupy half of the octahedral voids. If one $X$ atom and one $Y$ atom in each unit cell are replaced by a $Z$ atom,the molecular formula of the solid will be: