CBSE Class 12-science Answered

To know the number represented by Z we need to know about sharing of atoms as per its position in the unit cell. In body center cube number of atoms is 2 atoms calculated as corners 8 x 1/8 = 1 and body center = 1x1 therefore total 2 atoms per unit cell. In face centered cube there are total 4 atoms as Corners - 8x 1/8 = 1, face-6x ½ = 3 and in simple cube atoms are present only in the corners 8 x 1/8 = 1 atom per cube. Simple cube has least number of atoms.