Which of the following oxides behaves as conductor or insulator depending upon temperature ?
(i) TiO (ii) SiO₂ (iii) TiO₃ (iv) MgO
​Give reasons for your answer .

SiO₂ behaves as conductor as well as insulator. At lower temperature it behaves like a insulator and at high temperature they show conducting behaviour. Because its a semiconductor. Semiconductors are insulators at low temperature and in pure state. But when they are doped with group 13 or group 15 they behave as a good conductor.