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

• TiO₃ behaves as conductor or insulator mainly because of the energy gap variability between valence band and conduction band. This gap changes in accordance with temperature; as the temperature increases so decreases the gap and it leads to more conductive nature which is opposite in case of lowering of temperatures.

• Options (i) TiO (ii) SiO₂ and (iv) MgO are incorrect .

• TiO which behaves like a metal also can conduct electricity because the d-electrons are partially filled and leads to electrical conductivity.

• (ii) SiO₂ (quartz) is a network -solid which is covalent in nature and always behave as an insulator.

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• And (iv) MgO is an ionic crystalline solid which means it acts as an insulator in the solid-state and conducts electricity in the molten or aqueous state.

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