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

For a crystal,the first-order Bragg reflection of $X$-rays with a wavelength of $2.29 \times 10^{-10} \ m$ occurs at an angle of $27^\circ 8'$. Calculate the distance between two parallel planes.

The density of $Na$ is $0.613 \ g \ cm^{-3}$. If the edge length of the unit cell of $Na$ is $5 \ \mathring{A}$,the effective number of atoms of $Na$ per unit cell is (Atomic weight of $Na = 23 \ u$)

The density of chromium metal is $7 \ g \ cm^{-3}$. If the edge length of the unit cell is $300 \ pm$, identify the type of unit cell. (Atomic mass of $Cr = 52$)

If $M$ is the atomic mass of an element and $a$ is the edge length of the unit cell,then the formula to calculate the density $\rho$ is:

An element with molar mass $2.7 \times 10^{-2} \ kg \ mol^{-1}$ forms a cubic unit cell with edge length $405 \ pm$. If its density is $2.7 \times 10^{3} \ kg \ m^{-3},$ the radius of the element is approximately......... $\times 10^{-12} \ m$ (to the nearest integer).