A Metal crystallizes into two cubic phases, face-centred cubic and body centred cubic whose unit cell lengths are `3.5overset(0)A` and `3.0overset(0)A` respectively. Calculate the ratio of the densities of fcc and bcc crystals.

Explanation

Density of unit cell (d) = `zxxM//(N_Axxa^3)`
Density of fcc unit cell = `4xxM//[N_Axx(3.5A^0)^3)`
Density of fcc unit cell = `4xxM//[N_Axx(3.5A^0)^3]`
Density of bcc unit cell = `2xxM//[N_Axx(3.0A^0)^3]`
Density of fcc/Density of bcc =108/85.75=1.259