Question

In the given sphere, the black spheres forms the first layer and red sphere forms the second layer and blue sphere forms the third layer.
The correct representation of the given arrangement of spheres is

• A. Hexagonal close packing
• B. Cubic close packing
• C. bcc close packing
• D. Square close packing

Answer 1

The correct option is B Cubic close packing

Given, the black spheres forms the first layer and red sphere forms the second layer and blue sphere forms the third layer.

The second layer (black) of spheres is placed in the interstices or depressions of the first-row spheres. The third layer (blue) is placed over the second layer covering the octahedral voids of the second layer so that the spheres of the third layer are not aligned with neither the first nor the second layer. Thus, all the three layers are not identical.
Hence, it gives ABCABC... type of arrangement. This structure is called cubic close packed (ccp) or face-centred cubic (fcc) structure.