Question
Chemistry Question on The solid state
ZnO is white when cold and yellow when heated. It is due to the development of
A
Frenkel defect
B
metal excess defect
C
Schottky defect
D
metal deficiency defect
Answer
metal excess defect
Explanation
Solution
ZnO turns yellow on heating as Zn ions move in interstitial sites and electrons also get entrapped in nearby interstitial sites to maintain electrical neutrality. As extra Zn ions are present in interstitial sites thus, it is metal excess defect.