Which of d-block elements can exhibit the highest possible oxidation state ?

Options

A. Fe
B. Rh
C. Os
D. both (2) and (3)

Explanation

To determine which d-block elements can exhibit the highest possible oxidation state, we need to analyze the oxidation states of various d-block elements and identify those that can reach +8.

### Step-by-Step Solution:

1. **Understanding Oxidation States**:
- The oxidation state of an element is a measure of the degree of oxidation of an atom in a compound. For d-block elements, oxidation states can vary widely due to the involvement of d electrons in bonding.

2. **Maximum Oxidation State**:
- The highest oxidation state for any element is typically determined by the number of valence electrons it can lose. For transition metals, this is generally up to +8, as they can utilize both their s and d electrons.

3. **Identifying Candidates**:
- The d-block elements that are known to exhibit high oxidation states include elements like Ruthenium (Ru), Rhodium (Rh), and Osmium (Os).

4. **Evaluating Specific Elements**:
- **Iron (Fe)**: Although it can exhibit oxidation states of +2 and +3, it cannot reach +8 due to its susceptibility to corrosion and atmospheric attack, which limits its stability in higher oxidation states.
- **Ruthenium (Ru)**: This element can attain a +8 oxidation state under certain conditions.
- **Rhodium (Rh)**: Similar to Ruthenium, Rhodium can also exhibit a +8 oxidation state.
- **Osmium (Os)**: Osmium is well-known for its ability to reach the +8 oxidation state and is stable in this oxidation state.

5. **Conclusion**:
- The d-block elements that can exhibit the highest oxidation state of +8 are Ruthenium (Ru), Rhodium (Rh), and Osmium (Os). Therefore, the correct answer is that both Rhodium and Osmium can attain the +8 oxidation state.

### Final Answer:
Ruthenium (Ru), Rhodium (Rh), and Osmium (Os) can exhibit the highest possible oxidation state of +8.