Calculate the volume of a $bcc$ unit cell if the radius of an atom present in it is $1.86 \times 10^{-8} \ cm$.

Calculate the number of atoms in $100 \, g$ of a crystal that crystallizes in an $fcc$ structure, given that its density is $10 \, g/cm^3$ and the edge length is $200 \, pm$.

Calculate the number of atoms present in a unit cell of an element having molar mass $190 \ g \ mol^{-1}$ and density $20 \ g \ cm^{-3}$. Given that $[a^3 \cdot N_A = 38 \ cm^3 \ mol^{-1}]$.

What is the atomic mass of an element with $BCC$ structure and density $10 \ g \ cm^{-3}$ having an edge length of $300 \ pm$?

Calculate the number of unit cells in $0.9 \ g$ of a metal if it forms a $bcc$ structure. Given: $\rho \times a^3 = 3 \times 10^{-22} \ g$.

For a crystal,the diffraction angle for the second-order diffraction is $2\theta = 90^{\circ}$. If the distance between two parallel planes is $2.28 \ \mathring{A}$,then the wavelength of the $X$-rays used for Bragg diffraction (in $\mathring{A}$) will be .........