Question

The yellow colour of $ZnO$ and conducting nature produced in heating is due to:

• A. Metal deficiency defect
• B. Metal excess defect due to the presence of extra cations at interstitial sites
• C. Impurity Defects
• D. All of the above

Answer 1

The correct option is B Metal excess defect due to the presence of extra cations at interstitial sites

On heating $ZnO$, it loses oxygen
$ZnO\stackrel{heating}{\to }Z{n}^{2+}+\frac{1}{2}{O}_2+2e^{-}$
Excess $Z{n}^{2+}$ ions moves to interstitial sites and the electrons to neighbouring interstitial sites.