ZnO shows yellow colour on Heating due to : — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Zinc oxide (ZnO) is a white solid at room temperature. Step 2: On heating, it loses oxygen reversibly to form a non-stoichiometric compound: ZnO --Δ--> Zn_(1+x)O + x/2 O2. The excess Zn^2+ ions and electrons occupy interstitial positions in the crystal lattice. Step 3: The trapped electrons in these anionic vacancies act as F-centers, absorbing light in the blue region of the visible spectrum and reflecting yellow light. Thus, the correct option is (d).