Ga (atomic mass 70 u ) crystallizes in a hexagonal close packed structure. The total number of voids in 0 . 581 g of Ga is ________ × 10 21 . (Round off to the Nearest Integer).

Step-by-step solution

HCP structure : Per atom, there will be one octahedral void ( OV ) and two tetrahedral voids ( TV ) . Therefore, total three voids per atom are present in HCP structure. → Therefore total no. of atoms of Ga will be- =   Mass     Molar   Mass   × N A = 0 . 581   g 70   g / mol × 6 . 023 × 10 23 → Now, total Number of voids = 3 × total no. of atoms = 3 × 0 . 581 70 × 6 . 023 × 10 23 = 14 . 99 × 10 21 ≃ 15 × 10 21