An element has a $BCC$ structure. The edge length of the unit cell is $288 \, pm$. If the density of the crystal is $7.2 \, g \, cm^{-3}$, what is the atomic mass of the element?

Fill in the blanks:
$1.$ Density of unit cell $(d) = ........$
$2.$ Mass of atoms present in unit cell $(m) = ........$

In a $CsCl$ crystal,the interionic distance between $Cs^+$ and $Cl^-$ ions is:

Calculate the edge length of a $bcc$ unit cell if the radius of the metal atom is $227 \ pm$.

When an electron in an excited atom jumps from the $L$ shell to the $K$ shell,$X$-rays are emitted. These $X$-rays undergo first-order diffraction at an angle of $7.75^{\circ}$ by a crystal with an interplanar spacing of $2.64 \ \mathring{A}$. Calculate the energy difference between the $K$ shell and the $L$ shell. $(\sin \ 7.75^{\circ} = 0.1349)$

$A$ metal has a $fcc$ structure. If the edge length of the unit cell is $200 \text{ pm}$, calculate the volume occupied by the particles in a unit cell.