Chemistry - Solid State Question with Solution | TestHub

For an fcc (face-centered cubic) structure, the packing efficiency is $74\%$.

The percentage of void volume in the fcc unit cell is $100\%-74\%=26\%$.

Let the total volume of the unit cell be $V$.

Void volume $=0.26V$

$0.26V=1.66\times 10^{-23}{\text{cm}}^3$

$V=\frac{1.66\times 10^{-23}}{0.26}{\text{cm}}^3$

$V=6.3846\times 10^{-23}{\text{cm}}^3\approx 6.385\times 10^{-23}{\text{cm}}^3$

Answer: $6.385\times 10^{-23}{\text{cm}}^3$