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Zno on heating turns yellow and becomes white when cold?? explain ncery 2 |
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Answer» Answer: Zno on heating turns YELLOW and becomes white when cold because When COLOURLESS ZnO is strongly HEATED, the metal atoms are deposited on CRYSTAL surface and anions 0^2- migrate to the surface producing vacancies at anion lattice points. These anions combine with Zn atoms forming ZnO and rclease clectrons. Zn+O^2- ---------> ZnO+2e^- These released electrons diffuse into the crystal and occupy vacant sites of anions and produce F- CENTRES. Due to these colour centres, ZnO turns yellow. |
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