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Question: Answered & Verified by Expert
A metallic element crystallizes into a lattice containing a sequence of hexagonal layers of ABABAB....... What percentage by volume of this lattice is empty space?
ChemistrySolid StateJEE Main
Options:
  • A 26%
  • B 74%
  • C 50%
  • D 85%
Solution:
2097 Upvotes Verified Answer
The correct answer is: 26%
Number of atoms in hcp is 6 per unit cell.

Packing fraction = 6× 4 3 πr 3 Base area×C

Base area =6×344r2

C=4r23

Packing fraction =π32=0.74

Void % =1-0.74×100=26%

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