Find the radius of an atom in $fcc$ unit cell having edge length $405 \ pm$. (in $pm$)

In a $NaCl$ crystal,the distance between $Na^+$ and $Cl^-$ ions is $2.814 \ \overset{\circ}{A}$ and the density of the crystal is $2.167 \ g/cm^3$. Calculate the value of Avogadro's number $(N_A)$.

Calculate the edge length of the unit cell of a metal which crystallises in a $bcc$ structure. (Radius of metal atom $= 173 \ pm$)

$A$ metal crystallises in $bcc$ lattice with unit cell edge length of $300 \ pm$ and density $6.15 \ g \ cm^{-3}$. The molar mass of the metal is

Find the molar mass of an element that crystallizes forming a unit cell structure having an edge length of $4 \times 10^{-8} \ cm$ and containing $4$ particles. (Density $\rho = 19.7 \ g \ cm^{-3}$)

Derive the formula to determine the density of a unit cell.