How can the crystal form of ice be examined?

An element (atomic mass $100 \ g/mol$) having $bcc$ structure has unit cell edge $400 \ pm$. Then density of the element is (in $g/cm^3$)

Calculate the radius of an atom of a metal forming an $fcc$ unit cell having an edge length of $360 \text{ pm}$. (in $\text{ pm}$)

Derive the expression for the density $(d)$ of a unit cell: $d = \frac{zM}{a^3 N_A}$.

Calculate the density of an element having molar mass $27 \ g \ mol^{-1}$ that forms $fcc$ unit cell. $[a^3 \cdot N_A = 38.5 \ cm^3 \ mol^{-1}]$ (in $g \ cm^{-3}$)

$X$-ray diffraction studies show that copper crystallises in an $fcc$ unit cell with cell edge of $3.608 \times 10^{-8} \ cm$. In a separate experiment,copper is determined to have a density of $8.92 \ g / cm^{3}$,calculate the atomic mass of copper.