Q. Copper crystallises in a face-centred cubic lattice with a unit cell length of 361 pm. What is the radius of copper atom in pm?
A) 157
B) 181
C) 108
D) 128
Explanation
[Solution from source] In fcc atoms touch along the face diagonal: 4r = √2a. r = 1.414 × 361/4 ≈ 128 pm. Using the bcc relation (√3a/4) gives 157 pm. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.