The yellow colour of ZnO and conducting nature produced in heating is due to — Solid State Chemistry Question

💡 Solution & Explanation

When ZnO is heated, it loses oxygen and forms a non-stoichiometric compound with excess zinc. The excess $Zn^{2+}$ ions are accommodated in interstitial sites and the electrons are trapped in neighboring interstitial sites. These trapped electrons (similar to F-centres) absorb light in the visible region, causing the yellow colour, and contribute to its conducting nature. Therefore, correct answer is C.