Question

Hexagonal close packed arrangement of ions is described as:
A. ABC ABA
B. ABC ABC
C. ABABA
D. ABBAB

Answer 1

Hint: The solid elements in nature occur in either the crystalline form or the amorphous form. The two of these structures differ in the arrangement of the ions and the molecules of the element. Both the amorphous form and the crystalline forms have different properties and packing of the overall structure which in turn gives them their distinct nature.

Complete step by step answer:
The solids can broadly be categorised as amorphous or crystalline based on the packing of this structure in the lattice space. The crystalline solids have a more defined structure than their amorphous counterparts. The crystals of the crystalline are distinct in arrangements and can be categorized in various categories.
All these categories contain a distinct arrangement of the atoms in the crystal lattice. All the factors like the intermolecular distance and the positions of the atoms are fixed for a specific crystal. These different arrangements are what gives rise to the different structures of crystal.
ABAB is the hexagonal close packing arrangement. Each sphere is in contact with six spheres. The coordination number of the arrangement is 6. The centres of the spheres that surround the sphere are found to be at the corners of the regular hexagon.

So, the correct answer is Option C.

Note: The crystals in the solids are categorised as the unit cell structure. These are seven in the count and are namely cubic, tetragonal, orthorhombic, trigonal, monoclinic, triclinic, hexagonal.
All these primitive crystals are differentiated based on their size, edge and the angle which the edges subtend with each other.