Answer:
407pm is the edge length of the cubic unit cell
Explanation:
In a Face-centered cubic unit you can use Pythagoras theorem to relate edge length with atomic radius (As you can see in the picture), thus:
e²+e² = (4r)²
2e² = 16r²
e = √8 r
If the atomic radius of the atom is 144pm:
e = √8 ×144pm
e = 407ppm
407pm is the edge length of the cubic unit cell
