$A$ face-centered cubic $(FCC)$ solid of an element (atomic mass $60$) has a cubic edge length of $4 \times 10^{-8} \, cm$. If Avogadro's number is $6 \times 10^{23} \, mol^{-1}$,then the density of the solid is:

Iron oxide $FeO$ crystallises in a cubic lattice with a unit cell edge length of $5.0 \ \mathring{A}$. If the density of the $FeO$ in the crystal is $4.0 \ g \ cm^{-3}$,then the number of $FeO$ units present per unit cell is $...........$ (Nearest integer).
Given: Molar mass of $Fe$ and $O$ is $56$ and $16 \ g \ mol^{-1}$ respectively.
$N_{A} = 6.0 \times 10^{23} \ mol^{-1}$

The number of atoms in $100 \ g$ of an $fcc$ crystal with density $d = 10 \ g/cm^3$ and cell edge equal to $100 \ pm$ is equal to

Radius of cation and anion are $2.5 \ \mathring{A}$ and $2.6 \ \mathring{A}$ respectively. If a cubic crystal system is prepared by combination of above cation and anion then edge length of unit cell is ................ $\mathring{A}$ (Take $\sqrt{3} = 1.7$)

In the $x$-ray reflection $(n=1)$, the distance between two parallel planes of $NaCl$ is $280 \ pm$ and the diffraction angle is $5.2^{\circ}$. What is the wavelength of its light radiation? (Given: $\sin 5.2^{\circ} = 0.09$)

Derive the expression for the density $(d)$ of a unit cell: $d = \frac{zM}{a^3 N_A}$.