In calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion (Ca^2+) and fluoride ion (F^-) are

1. 6 and 6

2. 8 and 4

3. 4 and 8

4. 4 and 2

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 2 neet Save WhatsApp Report

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Answer: 2. 8 and 4

Key idea: in the fluorite structure, \(Ca^{2+}\) forms an fcc lattice and \(F^-\) occupies all tetrahedral holes.

Each \(F^-\) is surrounded by 4 \(Ca^{2+}\) and each \(Ca^{2+}\) by 8 \(F^-\). Ratio of ions is 1:2, consistent with 8:4.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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