The correct statement (s) for cubic close packed (ccp) three dimensional structure is (are)

Options

A. The number of the neighbours of an atom present in the topmost layer is 12
B. The efficiency of atom packing is `74%`
C. The number of octahedral and tetrahedral voids per atom are 1 and 2 respectively
D. The unit cell edge length is `2sqrt(2)` times the radius of the atom

Answer

B, C, D

Explanation

Except for statement (a), all others are correct. For top layer, co- ordination number cannot be 12 becaue in both cubic and hexagonal close packed spheres, the top layer has no layer above it