Find the number of tetrahedral voids per atom in a crystal lattice.

What is the percentage of void space in $hcp$ and $ccp$ structures (in $\%$)?

In a face-centred cubic $(FCC)$ unit cell,what is the total volume occupied by the atoms?

Calculate the total volume occupied by all particles in a $fcc$ unit cell if the volume of unit cell is $5.2 \times 10^{-23} \ cm^3$.

What is the percentage of space occupied in a $bcc$ arrangement (in $\%$)?

In crystalline silicon,$Si$ atoms occupy all the $ccp$ sites and every alternate tetrahedral void. The value of packing efficiency is closest to $....\%$