QuestionSolid state / radius ratio
When the radius ratio in an ionic crystal lies between 0.732 – 0.999, the coordination number will be:
- (a) 3
- (b) 4
- (c) 6
- (d) 8
Answer: (d) 8
r⁺/r⁻ limits: 0.155–0.225 → CN 3; 0.225–0.414 → 4; 0.414–0.732 → 6; 0.732–1.0 → CN 8 (cubic, e.g. CsCl) → (d).