`H_2 S` is not a/an

Options

A. Reducing agent
B. Acidic
C. Oxidising agent
D. None of these

Explanation

To determine what `H2S` (hydrogen sulfide) is not, we need to analyze its properties and behavior in chemical reactions.

### Step-by-Step Solution:

1. **Identify the Composition of H2S**:
- Hydrogen sulfide consists of two hydrogen atoms and one sulfur atom. The molecular formula is `H2S`.

2. **Determine the Oxidation States**:
- In `H2S`, the oxidation state of hydrogen (H) is +1, and the oxidation state of sulfur (S) is -2. This can be calculated as follows:
- Let the oxidation state of sulfur be x.
- The equation for the overall charge is:
\[ 2(+1) + x = 0 \implies 2 + x = 0 \implies x = -2 \]
- Therefore, the oxidation state of sulfur in `H2S` is -2.

3. **Evaluate the Reducing Agent Property**:
- A reducing agent is a substance that donates electrons in a chemical reaction, thereby reducing another substance. Since sulfur in `H2S` has a low oxidation state (-2), it can act as a reducing agent.

4. **Evaluate the Acidic Property**:
- Hydrogen sulfide can act as a weak acid. It can donate protons (H+) in solution, forming HS- and S2- ions. Thus, it does have acidic properties.

5. **Evaluate the Oxidizing Agent Property**:
- An oxidizing agent is a substance that gains electrons in a chemical reaction, thereby oxidizing another substance. Since sulfur in `H2S` is already in a low oxidation state (-2), it cannot act as an oxidizing agent.

6. **Conclusion**:
- Based on the analysis, `H2S` is not an oxidizing agent.

### Final Answer:
`H2S` is not an oxidizing agent.