Question

silver crystallises in fcc unit cell. If the radius of silver atom is 145pm, what is the length of each side of unit cell?

Answer 1

As silver crystallises in fcc, the length of one face diagonal equals to 4 times the radius of silver i.e.,
4r = 1.4*a            where r=radius of silver & a=side of unit cell
4*145 = 1.4*a
a = 4*145/1.4 = 414.28 pm               where square root of 2 ~ 1.4