Q. An example of a non-stoichiometric oxide when heated is

2265 179 KEAMKEAM 2019The Solid State Report Error

A

BeO

5%

B

ZnO

78%

C

MgO

6%

D

CaO

6%

E

$L i_{2} O$

6%

Solution:

An example of a non-stoichiometric oxide when heated is $Z n O$ . Zinc oxide is white in colour at room temperature.

On heating, it loses oxygen and turns yellow.

$Z n O ⟶ heating Z n^{2 +} + \frac{1}{2} O_{2} + 2 e^{-}$

Now, there is excess of zinc in the crystal and its formula become $Z n_{1 + x} O$ . The excess $Z n^{2 +}$ ions move to interstitial sites and the electron to the neighbouring interstitial sites.