Which method is used to determine the edge length of a unit cell?

An element has a crystalline structure where the unit cell is a cube with one atom at each corner and two atoms on its body diagonal. If the volume of this unit cell is $24 \times 10^{-24} \, cm^3$ and the density of the element is $7.2 \, g \, cm^{-3}$,then the number of atoms present in $200 \, g$ of the element is:

How many unit cells are present in a cube-shaped ideal crystal of $NaCl$ of mass $1 \ g$?

An element crystallizes in an $f.c.c.$ structure with a unit cell edge length of $200 \, pm$. If $200 \, g$ of this element contains $24 \times 10^{23}$ atoms,calculate its density in $\text{g cm}^{-3}$.

The edge length of the unit cell of a metal $(M_W = 24 \, g \, mol^{-1})$ having a cubic structure is $4.53 \, \mathring{A}$. If the density of the metal is $1.74 \, g \, cm^{-3}$,then the effective number of atoms in the unit cell is :- $(N_A = 6 \times 10^{23} \, mol^{-1})$

An element occurs in the body-centred cubic $(BCC)$ structure with an edge length of $288 \ pm$. The density of the element is $7.2 \ g \ cm^{-3}$. The number of atoms present in $208 \ g$ of the element is nearly: