The effective radius of an iron atom is `1.42 Å`. It has a rock-salt structure. Calculate its density (Fe = 56)

Explanation

Due to rock-salt (fcc) structure, number of atoms in a unit cell (z) = 4
Thus, `d ("density") = (zM)/(a^(3)N_(0)) " " a = 2 sqrt2 r = 2 sqrt2 xx 1.42 xx 10^(-8) cm`
`:. D = (4 xx 56)/(6.02 xx 10^(23) xx (2 sqrt2 xx 1.42 xx 10^(-8))^(3)) = 5.743 g //cm^(3)`