In aqueous solution, `H_(2)` will not reduce :

Options

A. `Fe^(3+)`
B. `Cu^(2+)`
C. `Ag^(+)`
D. `Zn^(2+)`

Answer

To solve the question of which cation `H2` will not reduce in an aqueous solution, we need to analyze the reduction potentials of the given cations. The reduction potential indicates the tendency of a species to gain electrons (be reduced).

### Step-by-Step Solution:

1. **Understand Reduction Potentials**:
- The reduction potential of a species is a measure of its ability to be reduced. A higher (more positive) reduction potential means that the species can be reduced by a substance with a lower reduction potential.

2. **Identify the Reduction Potentials**:
- For the cations in question:
- **Ag⁺**: Reduction potential = +0.8 V
- **Cu²⁺**: Reduction potential = +0.34 V
- **Fe³⁺**: Reduction potential = +0.771 V
- **Zn²⁺**: Reduction potential = -0.76 V
- The reduction potential for hydrogen ions (H⁺) to hydrogen gas (H₂) is 0 V.

3. **Compare Reduction Potentials**:
- Compare the reduction potentials of the cations with that of hydrogen:
- Ag⁺ (0.8 V) > H⁺ (0 V) → Can be reduced by H₂
- Cu²⁺ (0.34 V) > H⁺ (0 V) → Can be reduced by H₂
- Fe³⁺ (0.771 V) > H⁺ (0 V) → Can be reduced by H₂
- Zn²⁺ (-0.76 V) < H⁺ (0 V) → Cannot be reduced by H₂

4. **Conclusion**:
- Since Zn²⁺ has a lower reduction potential than hydrogen, it cannot be reduced by hydrogen in an aqueous solution. Therefore, the answer to the question is **Zn²⁺**.

### Final Answer:
In aqueous solution, `H₂` will not reduce **Zn²⁺**.