Atoms of element $B$ form a $ccp$ lattice and atoms of element $A$ occupy $\frac{1}{2}$ of the tetrahedral voids. What is the formula of the compound formed by elements $A$ and $B$?

In a face-centred cubic arrangement of $A$ and $B$ atoms,$A$ atoms are at the corners of the unit cell and $B$ atoms are at the face centres. If one of the $A$ atoms is missing from one corner of the unit cell,what is the simplest formula of the compound?

The percentage of unoccupied volume in a simple cubic cell is (in $\%$)

Calculate the packing efficiency in a body-centred cubic $(BCC)$ structure.

In a binary compound,atoms of element $A$ form a $hcp$ structure and those of element $M$ occupy $2/3$ of the tetrahedral voids of the $hcp$ structure. The formula of the binary compound is

Calculate the volume occupied by all atoms in a $bcc$ unit cell if the volume of the unit cell is $1.5 \times 10^{-22} \ cm^3$.