Chemistry | MHT CET 2016 | Discussion Page

In face centred cubic unit cell, what is the volume occupied?

$\frac{4}{3} \pi r^{3}$

$\frac{8}{3} \pi r^{3}$

$\frac{16}{3} \pi r^{3}$

$\frac{64 r^{3}}{3\sqrt{3}}$

Option C

The volume occupied by the face centred cubic unit cell is $\frac{16}{3} \pi r^{3}$

Packing fraction or volume occupied

$Z_{eff}\times$ volume of c-atom = $\frac{Z_{eff}\times\frac{4}{3}\pi r^{3}}{a^{3}}$

for fcc, $Z_{eff}=4=\frac{4\times\frac{4}{3}\pi r^{3}}{a^{3}}$ (where , a=1)

= $\frac{16}{3} \pi r^{3}$

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