Q10 / 54 · JEE Advanced 2016 (Paper 2) · Chemistry

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

  • A
    The number of the nearest neighbours of an atom present in the topmost layer is 12
  • Correct answer
    B
    The efficiency of atom packing is 74%
  • Correct answer
    C
    The number of octahedral and tetrahedral voids per atom are 1 and 2, respectively
  • Correct answer
    D
    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

Hence, the correct answer is options: 'B', 'C', 'D'.

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