NTA Abhyas JEE Main2020ChemistrySolid StatePractice
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?
Options
- A26%
- B74%
- C50%
- D85%
Correct answer
A. 26%
Step-by-step solution
Number of atoms in hcp is 6 per unit cell. Packing fraction = 6 × 4 3 πr 3 Base area × C Base area = 6 × 3 4 4 r 2 C = 4r 2 3 Packing fraction = π 3 2 = 0 . 74 Void % = 1 - 0 . 74 × 100 = 26 %