What is the total number of spheres that surround the tetrahedral hole in a close-packed three-dimensional structure?

Calculate the total volume occupied by all particles in a $fcc$ unit cell if the volume of unit cell is $5.2 \times 10^{-23} \ cm^3$.

The number of tetrahedral voids present in $0.5 \ mole$ of $hcp$ crystal structure is:

If the anion $(A)$ forms a hexagonal closest packing and the cation $(C)$ occupies only $2/3$ of the octahedral voids in it,then the general formula of the compound is :-

Atoms of element $B$ form $hcp$ lattice and those of the element $A$ occupy $2/3$ of tetrahedral voids. What is the formula of the compound formed by the elements $A$ and $B$?

The number of octahedral void$(s)$ per atom present in a cubic close-packed structure is