MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

In a face-centered cubic (fcc) crystal lattice, the coordination number is defined as the number of nearest neighbouring spheres for any given particle. Considering a face-centered atom, it is in contact with 4 corner atoms in its own plane. Additionally, it is in contact with 4 face-centered atoms in the plane immediately above it and 4 face-centered atoms in the plane immediately below it. Total number of nearest neighbours = 4 + 4 + 4 = 12. Thus, the coordination number for any particle in an fcc lattice is 12. Answer: 12