What is the total number of atoms in a $BCC$ crystal lattice having $1.8 \times 10^{20}$ unit cells?

$A$ compound $M_pX_q$ has a cubic close packing $(ccp)$ arrangement of $X$. Its unit cell structure is shown below. The empirical formula of the compound is

What is the volume occupied by particles in $BCC$ structure if '$a$' is the edge length of the unit cell?

$A$ cubic structure is formed where atoms of element $X$ are occupied at the corners of the cube and also at the face centers. Atoms of element $Y$ are present at the body center and at the edge centers. If all the atoms are removed along a plane passing through the middle of the cube (bisecting the four edges), the formula will become

What is the coordination number of $Zn$ in the crystal structure of $Zn$?

$A$ compound is formed by elements $A$ and $B$. This crystallises in the cubic structure where the $A$ atoms are at the corners of the cube and $B$ atoms are at the body centres. The simplest formula of the compound is