(a) Some of the glass objects recovered from ancient monuments look milky instead of being transparent. Why?
(b) Iron (II) oxide has a cubic structure and each side of the unit cell is 5. If density of the oxide is 4 g cm-3, calculate the number of Fe2+ and O2- ions present in each unit cell.
[Atomic mass : Fe = 56 u, O = 16 u; Avogadro's number = 6.0231023 mol-1]