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🧪 Chemistry  ·  Solid State  ·  NEET & JEE

The radius ratio for a coordination number of 4 (tetrahedral void) lies in the range:

Answer: 0.225 to 0.414.

  • A 0.155 to 0.225
  • B 0.225 to 0.414
  • C 0.414 to 0.732
  • D 0.732 to 1.000

Correct answer: B. 0.225 to 0.414

Explanation: A cation with radius ratio between 0.225 and 0.414 relative to the anion fits into a tetrahedral void and has coordination number 4.

Cubic Unit Cells: Atom PositionsSimple CubicCN=6, 52.4% packedBody-Centred (BCC)CN=8, 68% packedFace-Centred (FCC)CN=12, 74% packed (densest)Corner atoms (shared by 8 cells) shown lighter; body/face-centre atoms shown solid

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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