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Question
What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 1/3rd of tetrahedral voids?
Solution
Number of tetrahedral voids formed = 2 × Number of atoms of element Y
Number of atoms of element Y in the ccp unit cell = 4
Number of tetrahedral voids formed = 2 × 4 = 8
Number of tetrahedral voids occupied by atoms of X = (1/3) × 8 = 8/3
Ratio of the numbers of atoms of X and Y = 8/3 : 4=2 : 3
Hence, the formula of the compound is X2Y3.
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