Single Choice

$$ZnO$$ is white when cold and yellow when heated. It is due to development of:

AFrenkel defect
Bmetal excess defect
Correct Answer
CSchottky defect
Dmetal deficiency defect

Solution

$$ZnO$$ turns yellow on heating as $$Zn^{2+}$$ ions move in interstitial sites and electrons also get entrapped in nearby interstitial sites to maintain electrical neutrality. As extra $$Zn^{2+}$$ ions are present in interstitial sites thus, it is metal excess defect.

SIMILAR QUESTIONS

Solid State

ZnO is white when cold and yellow when hot because it____.

Solid State

The appearance of colour in solid alkali metal halides is generally due to:

Solid State

Which of the following statements is/are correct ?

Solid State

Select the correct statement(s) regarding defects in solids:

Solid State

Analysis shows that nickel oxide has the formula $$Ni_{0.98}O_{1.00}$$. What fractions of nickel exist as $$Ni^{2+}$$ and $$Ni^{3+}$$ ions?

Solid State

Zinc oxide loses oxygen on heating according to the reaction. $$ZnO\xrightarrow { heat } Zn^ { 2+} +\frac { 1 }{ 2 } O_ 2+2e^-$$ It becomes yellow on heating because:

Solid State

Select the correct statement regarding F-centre.

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