Q. A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is 408 pm. The diameter of the metal atom is
A) 204 pm
B) 288 pm
C) 408 pm
D) 144 pm
Explanation
[Solution from source] In an fcc lattice atoms touch along the face diagonal: 4r = √2 a, so the diameter 2r = a/√2 = 408/1.414 ≈ 288 pm. 204 pm is just half the edge length, which is valid for simple cubic contact only along the edge. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.