Metal M of radius 50 nm is crystallized in fcc type and made cubical crystal such that face of unit cells aligned with face of cubical crystal. If the total number of metal atoms of M at all faces of cubical crystal is , then the area of one face of cubical crystal is . Find the value of A

(2)

Consider one face of unit cell as shown below

Number of atoms on one face

 (corners) (Per corner share) + 1(face center)  (face center share)

Given number of atoms on all faces

Given number of atoms on one face

 atoms

Number of unit cells at one face of crystal

So, number of unit cells at the edge of crystal

Now, edge length of unit cell

Edge length of cubical crystal

So, area of face of crystal