Which of the following oxides behaves as a conductor or insulator depending upon temperature?

1.  TiO

2.  SiO2

3.  TiO3

4.  MgO

 

Hint: Vanadium and titanium oxide show metallic or insulating properties depending upon temperature
 
Certain metal oxides like VO2, VO, VO3 and TiO3 show metallic or insulating properties depending upon temperature. As
 
temperature varies metallic or insulating property varies. This is due to variation in the energy gap between the conduction band
 
and valence band.