In a $A_x B_y$ crystal structure,$A^{+y}$ ions occupy all the tetrahedral voids and $B^{-x}$ ions form a $BCC$ unit cell. What is the formula of the compound?

$A$ compound is formed by elements $A$, $B$ and $O$. Atoms of oxygen form $ccp$ lattice. Atoms of $A$ (cation) occupy $\frac{1}{8}^{\text{th}}$ of tetrahedral voids and atoms of $B$ (cation) occupy half of octahedral voids. What is the molecular formula of the compound?

In a crystal,atoms of $A$ form an $FCC$ lattice,atoms of $B$ occupy all octahedral voids,and atoms of $C$ occupy $25\%$ of the tetrahedral voids. The possible molecular formula of the compound is:

The limiting radius ratio for a tetrahedral void is:

Show that in a cubic close packed $(ccp)$ structure,eight tetrahedral voids are present per unit cell.

What is the percentage of space occupied by spheres of equal size in $hcp$ and $ccp$ three-dimensional arrangements?