Chemistry - Solid State Question with Solution | TestHub

${\mathrm{V}}_1={\mathrm{a}}^3=(400\times 10^{-12}\mathrm{m}{)}^3=64\times 10^{-30}{\mathrm{m}}^3$
${\mathrm{V}}_2=\frac{\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}}{\mathrm{d}\mathrm{e}\mathrm{n}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{y}}=\frac{0.015\mathrm{k}\mathrm{g}}{7.5\times 10^{-3}{\mathrm{m}}^{-3}}$
$=2\times 10^{-6}{\mathrm{m}}^3$
where${\mathrm{V}}_1$is the volume of the unit cell and${\mathrm{V}}_2$that of the metal sample.
So number of unit cell$=\frac{\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\text{volume}}{\text{Volumeofunitcell}}=\frac{2\times 10^{-6}{\mathrm{m}}^3}{64\times 10^{-30}{\mathrm{m}}^3}$
$=3.125\times 10^{22}$