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

Options

A. TiO
B. `SiO_2`
C. `TiO_3`
D. MgO

Answer

To determine which of the following oxides behaves as a conductor or insulator depending on temperature, we need to analyze the properties of each oxide mentioned.

### Step-by-Step Solution:

1. **Understanding Conductors and Insulators**:
- Conductors allow the flow of electrons easily, while insulators restrict the flow of electrons. This distinction is crucial for determining the behavior of the oxides.

2. **Analyzing Titanium Oxide (TiO₂)**:
- Titanium oxide is a metal oxide. In its solid form, the electrons are tightly bound, meaning there are no free electrons available for conduction. Therefore, titanium oxide is not a good conductor in solid form.

3. **Analyzing Silicon Dioxide (SiO₂)**:
- Silicon dioxide is known to be a very good insulator. The electrons in silicon dioxide are also restricted in their flow, making it a poor conductor of electricity.

4. **Analyzing Magnesium Oxide (MgO)**:
- Magnesium oxide is an ionic crystal solid that acts as an insulator in its solid form. It can conduct electricity only when it is in molten form, but in solid form, it does not conduct well.

5. **Analyzing Ctenition (CeO₂)**:
- Ctenition (cerium oxide) has a significant gap between its conduction band and valence band. At low temperatures, the electrons are in the valence band and cannot move freely, making it behave as an insulator. However, as the temperature increases, electrons gain energy and can jump to the conduction band, allowing them to move freely and conduct electricity. Thus, ctenition behaves as a conductor at high temperatures and as an insulator at low temperatures.

6. **Conclusion**:
- Among the oxides analyzed, **ctenition (CeO₂)** is the only oxide that behaves as a conductor at high temperatures and as an insulator at low temperatures.

### Final Answer:
Ctenition (CeO₂) behaves as a conductor or insulator depending upon temperature.