Question

Which one of the following is the most efficient packing arrangement?
AAA type in 2 D
AAA type in 3D
ABAB type in 2D
ABCABC type in 3 D​

Answer 1

The most effective packing arrangement among the following is:

(i) ABC ABC type in 3 D​

- The packing arrangement ABC ABC type in 3 D is equivalent to cubic closed packing (ccp) or face centred cubic (fcc) lattice.

- The efficiency of fcc is the highest among all the arrangements, i.e., 74%.

- Hence, ABC ABC type arrangement in 3 D​ is the most efficient.

Answer 2

In three dimensional packing ABCABC type of packing is efficient.

Option (D) is correct.

Explanation:

• Three dimensional packing takes place in cubid closed pack and face centered cubic structures.
• In these structure one layer is place above the other and so on.
• In this packing the sphere of first and second layers are aligned while the spheres of third layer are not aligned with the rest of the two layers.
• Similarly fourth layer gets aligned with the first layer and this pattern is called ABCABC packing.