A sulphur containing species that can not be a reducing agent is :-

Options

A. `SO_(2)`
B. `SO_(3)^(-2)`
C. `H_(2)SO_(4)`
D. `S_(2)O_(3)^(2-)`

Answer

To determine which sulfur-containing species cannot act as a reducing agent, we need to analyze the oxidation states of sulfur in various compounds. A reducing agent is a species that can donate electrons and thus be oxidized, which means it must have a lower oxidation state that can be increased.

### Step-by-Step Solution:

1. **Understand Oxidation States of Sulfur**:
- Sulfur can exist in various oxidation states: -2, 0, +2, +4, and +6.
- The higher the oxidation state, the less likely it is to act as a reducing agent since it has already been oxidized.

2. **Identify the Compounds**:
- We need to evaluate different sulfur-containing compounds to see their oxidation states and determine if they can act as reducing agents.

3. **Analyze Each Compound**:
- **Compound A**: Let's say it's H2S (Hydrogen sulfide).
- Oxidation state of S = -2 (since H is +1).
- Can be oxidized to 0, +2, +4, or +6. **Can act as a reducing agent**.

- **Compound B**: Let's say it's SO2 (Sulfur dioxide).
- Oxidation state of S = +4.
- Can be oxidized to +6. **Can act as a reducing agent**.

- **Compound C**: Let's say it's H2SO4 (Sulfuric acid).
- Oxidation state of S = +6.
- Cannot be oxidized further since +6 is the highest oxidation state. **Cannot act as a reducing agent**.

- **Compound D**: Let's say it's S2O3 (Thiosulfate).
- In thiosulfate, sulfur exists in different oxidation states.
- One sulfur can be in +6 and another in -2. The -2 sulfur can be oxidized to +6. **Can act as a reducing agent**.

4. **Conclusion**:
- After evaluating all the compounds, we find that H2SO4 (sulfuric acid) is the only sulfur-containing species that cannot act as a reducing agent because it is already in the maximum oxidation state of +6.

### Final Answer:
The sulfur-containing species that cannot be a reducing agent is **H2SO4 (sulfuric acid)**.