Hexagonal close packed arrangement of ions is described as

In a cubic close packed structure,the fractional contributions of an atom at the corner and at the face in the unit cell are,respectively:

If the distance between the corner and the center of a cube is $x$,then the tetrahedral void will be at a distance of .... from the corner of the cube.

Atoms $A$ are arranged in an $FCC$ system,and atoms $B$ occupy all the octahedral voids and half of the tetrahedral voids. The formula of the compound is:

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:

Atoms of element $A$ occupy $\frac{1}{3}$ of the octahedral voids,while atoms of element $B$ form an $hcp$ structure. Determine the formula of the compound formed by $A$ and $B$.