Maximum oxidation state is shown by:

Options

A. `Os`
B. `Mn`
C. `Cr`
D. `Co`

Answer

To determine which element shows the maximum oxidation state among the given options, we will analyze the electronic configurations of each element and calculate their maximum possible oxidation states.

### Step-by-Step Solution:

1. **Identify the Elements and Their Atomic Numbers:**
- The elements provided are Osmium (Os), Manganese (Mn), Chromium (Cr), and Cobalt (Co).
- Their atomic numbers are:
- Osmium (Os) - 76
- Manganese (Mn) - 25
- Chromium (Cr) - 24
- Cobalt (Co) - 27

2. **Write the Electronic Configuration:**
- **Osmium (Os):**
- Atomic Number: 76
- Electronic Configuration: [Xe] 4f14 5d6 6s2
- **Manganese (Mn):**
- Atomic Number: 25
- Electronic Configuration: [Ar] 3d5 4s2
- **Chromium (Cr):**
- Atomic Number: 24
- Electronic Configuration: [Ar] 3d5 4s1
- **Cobalt (Co):**
- Atomic Number: 27
- Electronic Configuration: [Ar] 3d7 4s2

3. **Calculate Maximum Oxidation States:**
- **Osmium (Os):**
- Total electrons that can be lost = 6 (from 5d) + 2 (from 6s) = 8
- Maximum oxidation state = +8
- **Manganese (Mn):**
- Total electrons that can be lost = 5 (from 3d) + 2 (from 4s) = 7
- Maximum oxidation state = +7
- **Chromium (Cr):**
- Total electrons that can be lost = 5 (from 3d) + 1 (from 4s) = 6
- Maximum oxidation state = +6
- **Cobalt (Co):**
- Total electrons that can be lost = 7 (from 3d) + 2 (from 4s) = 5
- Maximum oxidation state = +5

4. **Compare the Maximum Oxidation States:**
- Osmium: +8
- Manganese: +7
- Chromium: +6
- Cobalt: +5

5. **Conclusion:**
- The element that shows the maximum oxidation state among the given options is **Osmium (Os)** with an oxidation state of +8.

### Final Answer:
The maximum oxidation state is shown by **Osmium (Os)**.

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