Most common oxidation states shown by cerium are

Options

A. `+2, +4`
B. `+3, +4`
C. `+3, +5`
D. `+2, +3`

Answer

To determine the most common oxidation states shown by cerium, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Element**:
- Cerium (Ce) is an f-block element, specifically a lanthanide.

2. **Determine the Electronic Configuration**:
- The electronic configuration of cerium is:
- \( \text{[Xe]} 4f^2 5s^2 \)
- This indicates that cerium has 2 electrons in the 4f subshell and 2 electrons in the 5s subshell.

3. **Analyze Possible Oxidation States**:
- Cerium can lose electrons from both the 4f and 5s subshells.
- When cerium loses 3 electrons (2 from 4f and 1 from 5s), it achieves a +3 oxidation state.
- When cerium loses 4 electrons (2 from 4f and 2 from 5s), it achieves a +4 oxidation state.

4. **Common Oxidation States**:
- The most common oxidation states for cerium are therefore +3 and +4.
- The +4 oxidation state is particularly stable as it leads to a noble gas configuration (similar to xenon).

5. **Conclusion**:
- The most common oxidation states shown by cerium are +3 and +4.

### Final Answer:
The most common oxidation states shown by cerium are +3 and +4.