In the Bragg's equation for diffraction of $X$-rays, $n$ represents:

An element crystallizes in an $f.c.c.$ structure with a unit cell edge length of $200 \, pm$. If $200 \, g$ of this element contains $24 \times 10^{23}$ atoms,calculate its density in $\text{g cm}^{-3}$.

Calculate the volume of a simple cubic unit cell if the radius of the particle in it is $400 \ pm$.

An element has a $bcc$ structure with a cell edge of $288 \ pm$. The density of the element is $7.2 \ g \ cm^{-3}$. What is the atomic mass of the element?

At $100\, ^\circ C$,copper $(Cu)$ has $FCC$ unit cell structure with cell edge length $x\, \mathring{A}$. What is the approximate density of $Cu$ (in $g\, cm^{-3}$) at this temperature? [Atomic mass of $Cu = 63.55\, u$]

Copper crystallises in $fcc$ structure with a unit cell length of $361 \ pm$. What is the radius of copper atom? ............ $pm$