Ammonium chloride crystallizes in a body-centered cubic lattice with an edge length of the unit cell of $390 \ pm$. If the size of the chloride ion is $180 \ pm$,the size of the ammonium ion would be ........... $pm$.

What is the molar mass of a metal with a $BCC$ structure having a density of $10 \ g \ cm^{-3}$ and an edge length of $200 \ pm$?

An element crystallises in an $fcc$ unit cell with a cell edge length of $3.608 \times 10^{-8} \text{ cm}$. The density of the element is $8.92 \text{ g cm}^{-3}$. Calculate the atomic mass of the element $(N_A = 6.022 \times 10^{23} \text{ mol}^{-1})$. (in $\text{ g/mol}$)

To obtain a diffraction peak for a crystalline solid with interplane distance equal to the wavelength of incident $X$-ray radiation,the angle of incidence should be $....\,^{\circ}$

Solid $AB$ has $NaCl$ type structure. If the radius of $A^{+}$ and $B^{-}$ are $0.5 \ \mathring{A}$ and $1.5 \ \mathring{A}$ respectively and the formula mass of $AB$ is $48 \ g/mol$,what is the density of $AB$ solid? $(N_A = 6 \times 10^{23})$

Derive the formula to determine the density of a unit cell.