In a $ccp$ arrangement,what is the number of octahedral voids per atom?

The number of tetrahedral and octahedral voids in a $CCP$ unit cell are respectively:

In a cubic close packing,the unit cell has...

What is the total volume occupied by atoms in a $bcc$ unit cell (in $\%$)?

$Ga$ (atomic mass $70 \, u$) crystallizes in a hexagonal close packed structure. The total number of voids in $0.581 \, g$ of $Ga$ is $\dots \dots \dots \dots \dots \times 10^{21}$. (Round off to the Nearest Integer).

In a face-centred cubic $(FCC)$ unit cell,what is the total volume occupied by the atoms?