Question

Calculate the volume of fcc unit cell in terms of the atomic radius

Answer 1

In fcc lattice
$\sqrt{2} a = 4r$
where 'r' is the radius of atoms in unit cell and 'a' is edge length of the unit cell.
We know that volume of unit cell is
${a}^{3}$
Hence
$a = 2 \sqrt{2} r$
Hence the volume of unit cell in terms of radius is
$({2 \sqrt{2}r })^{3}$
i.e
${16root2r}^{3}$
So here is your answer.
Good luck☺