Question

The arrangement ABC ABC ABC ____ is referred as:
A. Octahedral close packing
B. Hexagonal close packing
C. Tetrahedral close packing
D. Cubic close packing

Answer 1

Hint: A crystal's geometry defines the arrangement of the spheres at infinite. In this arrangement, one unit is termed a lattice. A lattice shows the arrangement of particles in a crystal. A void defines the unoccupied space between two spheres.

Complete Step by Step Answer:
Let's discuss all the options one by one.
In cubic close packing, the spheres of molecules are at the adjacent position to each other such that each row containing spheres in a specific dimension is repetitive to the previous row. In this packing, a particular row's spheres don't fit into the depressions between two spheres at the adjacent positions in the previous row.

Cubic close packing is observed in copper, silver, etc. In cubic close packing, one unit cell's volume can be found by the formula of \[16\sqrt 2 {r^3}\]. The arrangement of the spheres in the cubic close packing is ABC-ABC-ABC. So, the arrangement is cubic close packing.
Therefore, option D is right.

Note: The other type of close packing is hexagonal close packing. In this packing, a particular row's spheres get fit into the voids of the previous row. This lattice is found in many metals such as zinc, and magnesium. The arrangement of spheres is of the type AB-AB AB. In this type of packing, a unit cell's volume can be found by the formula of \[24\sqrt 2 {r^3}\] .