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

The CORRECT statement(s) for cubic close packed (ccp) three dimensional structure is (are)
  1. The number of the nearest neighbours of an atom present in the topmost layer is 12
  2. The efficiency of atom packing is 74%
  3. The number of octahedral and tetrahedral voids per atom are 1 and 2, respectively
  4. The unit cell edge length is 22 times the radius of the atom

Solution

CCP is ABC ABC ..... type packing
A] In topmost layer, each atom is in contact with 6 atoms in same layer and 3 atoms below this layer.
B] Packing fraction =4×43 πr34r23=0.74
C] Each FCC unit has effective no of atoms = 4
Octahedral void = 4
Tetrahedral void = 8
D] 4r=a2

Asked in: JEE Advanced 2016 (Paper 2)

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