Strongest Oxidizing Agent

To determine the strongest oxidizing agent among the given options (CO2, SiO2, SnO2, and PbO2), we need to consider their oxidation states and their ability to gain electrons.

1. CO2 (Carbon Dioxide)
- Carbon in CO2 has an oxidation state of +4, while oxygen has an oxidation state of -2.
- Since carbon already has a high oxidation state, it cannot easily accept more electrons to further increase its oxidation state.
- Therefore, CO2 is not a strong oxidizing agent.

2. SiO2 (Silicon Dioxide)
- Silicon in SiO2 has an oxidation state of +4, while oxygen has an oxidation state of -2.
- Similar to CO2, silicon in SiO2 already has a high oxidation state and cannot easily accept more electrons.
- Thus, SiO2 is not a strong oxidizing agent.

3. SnO2 (Tin(IV) Oxide)
- Tin in SnO2 has an oxidation state of +4, while oxygen has an oxidation state of -2.
- Tin can accept two additional electrons to increase its oxidation state to +4.
- Therefore, SnO2 has the potential to act as an oxidizing agent.

4. PbO2 (Lead(IV) Oxide)
- Lead in PbO2 has an oxidation state of +4, while oxygen has an oxidation state of -2.
- Lead can accept four additional electrons to increase its oxidation state to +4.
- PbO2 has a higher ability to accept electrons compared to SnO2, making it a stronger oxidizing agent.

Conclusion: Among the given options, PbO2 (Lead(IV) Oxide) is the strongest oxidizing agent. It has a higher ability to accept electrons due to the presence of lead with an oxidation state of +4.