Q11 of 26 Page 1

Determine the type of cubic lattice to which ion crystal belongs if its unit cell has an edge length of 300pm and density of iron is 7.2g cm-1. [Atomic mass of Fe = 56 g mol-1; NA = 6.02 x 1023 mol-1]

Given: edge length = a = 300pm = 300 x 10-10 cm


Density = ρ= 7.2g cm-1


Atomic mass of Fe = M = 56 g mol-1


NA = 6.02 x 1023 mol-1



Where z = no., of atoms per unit cell



Since there are 2 atoms per unit cell, the ionic crystal is of body centre cubic(bcc) type.


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