Magnesium oxide has the NaCl structure and radii of `Mg^(2+)` and `O^(2–)` ions are 0.86 A and 1.24 A. Determine the density of magnesium oxide solid.

Explanation

In a unit cell, there are four unit of MgO and edge- length of the unit cell is
a = 2 (radius of cation + radius of anion)
= 2 (0.86 + 1.24) = 4.2 Å
Density `(rho)=(4x40)/(6.023xx10^(23)(4.2xx10^(10^(-8)))^(3))=3.585 g//cc`