Iron changes its crystal structure from bodycentred cubic to cubic close –packed structure when heated to 952^oC. Calculate the ratio of the density of the bcc crystal to that of ccp crystal, assuming that the metallic radius of the atom
remains same

.In the bcc packing, the space occupied is 68% of the total volume available while in ccp, the space occupied is 74%. This means that for the same volume, masses of the bcc and ccp are in the ratio of 68 : 74. As the volume is same, ratio of density is also same, viz., 68 : 74,
i.e.,d(ccp) / d(bcc) ​= 74/68​ = 0.919