13. iron changes the crystal structure from body-centered to cubic close-packed structure when heated to 916°c. calculate the ratio of the density of the bec cr

13. Iron changes the crystal structure from body-centered to cubic close-packed structure when heated to 916°C. Calculate the ratio of the density of the bec crystal to that of cop crystal, assuming that the metallic radius of the atom does not change: (a) 0.225 (b) 0.414 (c) 0.732 (d) 0.919