which of the following statements is (are) false? i. the layering in a hexagonal closest-packed structure is aba. ii. a body-centered cubic unit cell has four atoms per unit cell. iii. for unit cells having a simple cubic (primitive) structure, there would be one atom (net) for each unit cell. iv. atoms in a solid consisting of only one element would have six nearest neighbors if the crystal structure were a simple cubic array.
