An element with molor mass `27 g mol^(-1)` forms a cubic unit cell with edge length `4.05 xx 10^(-8) cm`. If its density is `2.7 g cm^(-3)`, what is the nature of the unit cell?

Answer

FCC

Explanation

`rho=(ZxxM)/(a^3xxN_A)` or `Z=(rhoxxa^3xxN_A)/M=((2.7 g cm^(-3))(4.05xx10^(-8)cm)^3(6.02xx10^23 mol^(-1)))/(27 g mol^(-1))=4`
Hence, it has face-centred cubic unit cell.