How many unit cells are present in $100 \ g$ of an element with $fcc$ crystal structure having density $10 \ g/cm^{3}$ and edge length $100 \ pm$?

Element $X$ crystallizes in a $12$ coordination face-centered cubic $(fcc)$ lattice. On applying high temperature,it changes to an $8$ coordination body-centered cubic $(bcc)$ lattice. Find the ratio of the density of the crystal lattice before and after applying high temperature. The atomic radius of $X$ is the same in both crystals.

What is the molar mass of a metal having a density of $8.57 \ g \ cm^{-3}$ and an edge length of $3.3 \ \mathring{A}$? (Packing efficiency $= 68 \%$)

Calculate the density of a metal which forms a simple cubic structure with an edge length of unit cell $336 \ pm$. ($90 \ g$ of metal contains $2.64 \times 10^{23}$ atoms) (in $g \ cm^{-3}$)

$X$-rays of wavelength $1 \ \mathring{A}$ are diffracted by the planes of particles in a metal. The second-order diffraction occurs at an angle of $60^{\circ}$. Calculate the distance between two parallel planes in $\mathring{A}$.

If an element having atomic number $96$ crystallises in a cubic lattice with a density of $10.3 \ g \ cm^{-3}$ and an edge length of $314 \ pm$, then the structure of the solid is: