Calculate the number of unit cells in $1 \ cm^3$ volume of metal if the unit cell edge length is $1.25 \times 10^{-8} \ cm$.

$Xe$ crystallizes in an $FCC$ structure. The edge length of its unit cell is $620 \, pm$. The radius of $Xe$ is $=$ ...... $pm$.

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

$X$-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 $\mathring{A}$.

Copper crystallizes in an $fcc$ lattice with a unit cell edge length of $361 \ pm$. What is the radius of the copper atom in $pm$?

Silver crystallises in $fcc$ lattice. If edge length of the cell is $4.07 \times 10^{-8} \ cm$ and density is $10.5 \ g \ cm^{-3}$,calculate the atomic mass of silver.