Which formula is used to calculate edge length $(a)$ in a $bcc$ structure,where $r$ is the radius of the atom?

An element with density $2.8 \ g \ cm^{-3}$ forms an $fcc$ unit cell having an edge length of $4 \times 10^{-8} \ cm$. Calculate the molar mass of the element.

$NaCl$ has a face-centered cubic structure. The edge length of the unit cell is $0.564 \ nm$. What is the density of sodium chloride? $.............. \ g/cm^3$ [$1 \ nm = 10^{-7} \ cm$]

$A$ crystalline solid of a pure substance has a face-centred cubic structure with a cell edge of $400 \ pm$. If the density of the substance in the crystal is $8 \ g \ cm^{-3}$, then the number of atoms present in $256 \ g$ of the crystal is $N \times 10^{24}$. The value of $N$ is

Calculate the volume of the unit cell when a metal having a density of $1 \ g \ cm^{-3}$ and a molar mass of $23 \ g \ mol^{-1}$ crystallizes to form a $bcc$ structure.

Calculate the number of atoms present in $1 \ g$ of an element if it forms an $fcc$ unit cell structure. [ $\varrho \times a^3 = 6.8 \times 10^{-22} \ g$ ]