Zinc oxide (white) is heated to high temperature for some time. Observe the following statement regarding…

Zinc oxide (white) is heated to high temperature for some time. Observe the following statement regarding above process I. Zinc oxide colour changes to pale yellow II. The type of defect formed is 'metal deficiency' III. Some $\mathrm{Zn}^{2+}$ and $e^{-}$are present in interstitial places
The correct statements are
  1. I,II only
  2. I,III only
  3. II,III only
  4. I,II,III

Solution

Zinc oxide is white in colour at room temperature on heating it loses oxygen and turns yellow.
$\mathrm{ZnO} \xrightarrow{\text { heating }} \mathrm{Zn}^{2+}+\frac{1}{2} \mathrm{O}_2+2 \mathrm{e}^{-}$
The excess $\mathrm{Zn}^{2+}$ ions more to interstitial site and electrons to neighbouring interstitial site. It is metal excess defect due to the pressure of extra cations at interstitial sites. So, (i) and (iii) are correct.

Asked in: AP EAMCET 2024 (22 May Shift 1)

Practice more Solid State questions on Aicharya