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InterviewSolution
| 1. |
Zinc oxide is white but it turns yellow on heating . Explain. |
| Answer» When ZnO is heated, it loses oxygen according ot reaction : ` ZnO to Zn^(2+) + 1/2 O^(2) + 2^(e-) Zn^(2+)` ions are entrapped in the interstitial voids and electrons in the neighbouring interestitial voids to maintain electrical neutulity . This gives rise to metal excess defect. Due to presence of electrons in the intersitial voids( F-centres), the colour is yellow as the remaining colours of while light are absorbed by these electrons. | |