Question

When heated above 916 degree C, iron change its crystal structure from bcc to cup structure without any changes in radius of atom. The ratio of the density of the crystal before heating and after heating is what?

Answer 1

Solution:

The bcc packing, the space occupies is 68% of the total volume available.

while in ccp, the space occupied is 74%.

This means that for the same volume masses of bcc and ccp are in the ratio of 68 : 74.

As the volume is same, ratio of density is also same thus 68 : 74

i.e. d(bcc)/d(ccp) = 68/74 = 0.919

(Answer)