Calculate the no. of particles (atoms) per unit cell in a FCC crystal lattice:

Explanation

Face - centred cubic : The lattice has 8 atoms on the corners and 6 atoms on the faces (one on each face).
Contribution by atoms on the corners `=(1)/(8)xx8=1`
Cotribution by atoms on the faces `= (1)/(2)xx6=3`
Number of atoms present in the unit cell `=1+3=4`.