The void space in an $fcc$ structure is ..........

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

In a solid compound,the atoms of $A$ form a face-centered cubic $(fcc)$ lattice,while atoms of $B$ occupy all octahedral voids and half of the tetrahedral voids. The molecular formula of the solid will be ........

The volume occupied by the atoms in a unit cell of hexagonal close packing $(HCP)$ or cubic close packing $(CCP)$ is equal to:

$A$ mineral consists of a cubic close-packed structure formed by $O^{2-}$ ions,where half the octahedral voids are occupied by $Al^{3+}$ and one-eighth of the tetrahedral voids are occupied by $Mn^{2+}$. The chemical formula of the mineral is

Calculate the total number of tetrahedral and octahedral voids in $0.4 \ mol$ of a compound having such voids in it.