Chemistry - Solid State Question with Solution | TestHub

$\mathrm{\rho }=\frac{{\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}\times \mathrm{M}\mathrm{w}}{{\mathrm{a}}^3\times 10^{-30}\times {\mathrm{N}}_{\mathrm{A}}}$
[For fcc,${\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}=4$/unit cell]
So,$\mathrm{M}\mathrm{w}=\frac{\mathrm{\rho }\times {\mathrm{a}}^3\times 10^{-30}\times {\mathrm{N}}_{\mathrm{A}}}{{\mathrm{Z}}_{\mathrm{e}\mathrm{f}\mathrm{f}}}$
$\left(\frac{\text{10}\text{.0}\text{g}{\text{cm}}^{-\text{3}}\text{×}{\text{(200)}}^{\text{3}}\text{×}{\text{10}}^{-\text{30}}{\text{cm}}^{\text{3}}\text{×}\text{6}\text{.02}\text{×}{\text{10}}^{\text{23}}}{\text{4}}\right)$
$=\mathrm{12\; g}$
As$\text{12}\text{g}$has number of atoms =$6.02\times 10^{23}$
So,$\text{100}\text{g}$has number of atoms =$\frac{6.02\times 10^{23}\times 100}{12}=5\times 10^{24}$