If a crystal changes from fcc to bcc , then calculate the ratio of density between fcc and bcc ? THERE IS NO CHANGE IN THE RADIUS OF THE ATOM.

We know,

D = Z m/a^{3}N_{A}

Where,

D is the density of the crystal

Z is the number of atoms in a unit cell ( 4 for FCC and 2 for BCC)

m is the atomic mass

a is the edge length of the cube

N_{A} is the avagadro’s number

Let D_{1} is the density for FCC structure and D_{2} be the density for BCC structure

Therefore,

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