The reason for greater range of oxidation state in actinoids is attributed to:

Options

A. The radioactive nature of actinoids
B. Actinoid contraction
C. 5f, 6d and 7s levels having comparable energies
D. 4f and 5d levels being close in energies

Answer

To solve the question regarding the reason for the greater range of oxidation states in actinoids, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Actinoids**:
- The actinoids are elements with atomic numbers from 90 (Thorium) to 103 (Lawrencium).

2. **Understand the Electronic Configuration**:
- The general electronic configuration of actinoids can be represented as [Rn] 5f¹⁻¹⁴ 6d⁰¹ 7s².
- This configuration indicates that the actinoids have electrons in the 5f, 6d, and 7s orbitals.

3. **Determine the Range of Oxidation States**:
- Actinoids exhibit a range of oxidation states, typically from +2 to +7, with +3 being the most common oxidation state.

4. **Analyze the Energy Levels of Orbitals**:
- The key to understanding the variable oxidation states lies in the energy levels of the 5f, 6d, and 7s orbitals.
- The energies of these orbitals are comparable, meaning the energy difference between them is small.

5. **Explain Electron Removal**:
- Due to the comparable energies of the 5f, 6d, and 7s orbitals, electrons can be removed from one or more of these orbitals.
- This ability to remove electrons from multiple orbitals contributes to the wide range of oxidation states observed in actinoids.

6. **Evaluate the Given Options**:
- Option 1: Radioactive nature - Not relevant to oxidation states.
- Option 2: Actinoid contraction - Not directly related to oxidation states.
- Option 3: Comparable energies of 5f and 7s - This is correct.
- Option 4: 4f and 5d levels - Not relevant.

7. **Conclusion**:
- The correct reason for the greater range of oxidation states in actinoids is due to the comparable energies of the 5f and 7s orbitals, allowing for the removal of electrons from these orbitals.

### Final Answer:
The reason for the greater range of oxidation states in actinoids is attributed to the comparable energies of the 5f and 7s orbitals.

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