Answer: ZnO.
- A NiO
- B Cu<sub>2</sub>O
- C Fe2O<sub>3</sub>
- D ZnO
Correct answer: D. ZnO
Explanation: ZnO develops a metal-excess defect on heating: extra Zn²⁺ in interstitial sites with electrons as carriers, making it n-type. NiO and Cu₂O are p-type; Fe₂O₃ behaves differently.
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.