An element occurs in two crystalline form `alpha` and `beta`. The `alpha`-from has an `fcc` with `alpha = 3.68 Å` and `beta`-from has a `bcc` with `a = 2.92 Å`. Calculate the ratio of their densities.

Explanation

`Z_(eff)` for `fc c = 4, Z_(eff)` for `bc c = 2`
Atomic volume of `alpha`-from `= ((3.68xx10^(-8))^(3)xxN_(A))/(4)`
Atomic volume of `beta`-from `= ((2.98xx10^(-8))^(3)xxN_(A))/(2)`
(As `Aw` is same, element is same), so the density ratio is
`rho_(alpha):rho_(beta) = V_(beta): V_(alpha) = (2.92)^(3)/(2):(3.68)^(3)/(4)`
`= 12.448:12.459`
`= 1:1`