Sodium metal crystallizes in $B.C.C.$ lattice with an edge length of $4.29 \ \mathring{A}$. The radius of the sodium atom is:

The density of the unit cell of $Li$ is $0.539 \ g/cm^3$ and the edge length of the unit cell is $3.5 \ \mathring{A}$. How many $Li$ atoms are present in a unit cell of lithium? (Atomic mass of $Li = 6.94 \ g/mol$)

For a crystal, the angle of diffraction $(2 \theta)$ is $90^{\circ}$ and the second order line has a $d$ value of $2.28 \ \text{Å}$. The wavelength (in $\text{Å}$) of $X$-rays used for Bragg's diffraction is

An element with molar mass $2.7 \times 10^{-2} \ kg \ mol^{-1}$ forms a cubic unit cell with edge length of $405 \ pm$. If its density is $2.7 \times 10^3 \ kg \ m^{-3}$, the number of atoms present in one unit cell of it is (Given : $N_{A}=6.023 \times 10^{23} \ mol^{-1}$)

The number of atoms in $4.5 \ g$ of a face-centred cubic crystal with edge length $300 \ pm$ is (Given: Density $= 10 \ g \ cm^{-3}$ and $N_A = 6.022 \times 10^{23}$)

Calculate the edge length of a unit cell that crystallizes to form a $BCC$ structure. (Radius of atom is $2.17 \times 10^{-8} \ cm$,$\sqrt{3} = 1.732$)