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InterviewSolution
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A compound formed by elements `A` and `B` crystallises in a cubic structure where `A` atoms are present at the corners of a cube and the `B` atoms are present at the face centres.The formula of the compound isA. `A_(2)B`B. `AB_(3)`C. `AB`D. `A_(3)B` |
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Answer» Correct Answer - 2 Each atom of a corner is shared between eight adjacent unit cells,Four unit cells in the same layer and four unit cells of the upper (or lower) layer.Therfore only `1//8`th of an atom (or molecule or ion) actually belongs to a particular unit cell). since the cubic unit cell `8` atoms on its corners ,the total number of `A` atoms inone unit cell is `=8xx(1)/(8)=1 "atom"` Each atom located at the face-centre is shared between two adjacent unit cell and hence only `1//2` of each atom belongs to a unit cell. Since each cubic unit cell has `6` atoms on its face-centres the total number of `B` atoms in one unit cell is `=6xx(1)/(2)=3 "atoms"` Thus the empericle formula of the compound is `AB_(3)`. |
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