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In a close-packed lattice of anions B, cations A occupy two-thirds of the octahedral voids. The formula of the compound is:

Answer: A₂B₃.

A A₂B₃
B A₃B₂
C AB₂
D A₂B

Correct answer: A. A₂B₃

Explanation: For N anions there are N octahedral voids; two-thirds filled gives 2N/3 cations, so A:B = 2N/3 : N = 2:3, i.e. A₂B₃.

The three cubic unit cells: Simple Cubic has atoms only at corners; Body-Centred adds one atom at the centre; Face-Centred adds one atom at the centre of each of the 6 faces, giving the highest packing efficiency.

Concept context

Explore the ordered world of crystalline solids: unit cells, packing, defects, and how structure determines electrical and magnetic properties.

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In a close-packed lattice of anions B, cations A occupy two-thirds of the octahedral voids. The formula of the compound is:

Concept context

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