If mercury is used as cathode in the electrolysis of NaCl solution, the ions discharged at cathode are

Options

A. `H^(+)`
B. `Na^(+)`
C. `OH^(-)`
D. `Cl^(-)`

Answer

To solve the question regarding the ions discharged at the cathode when mercury is used as the cathode in the electrolysis of sodium chloride (NaCl) solution, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electrolyte**:
- The electrolyte in this case is sodium chloride (NaCl) dissolved in water. When NaCl is dissolved, it dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻).

2. **Determine the Electrolysis Process**:
- During electrolysis, the ions in the solution migrate towards the electrodes. The sodium ions (Na⁺) move towards the cathode (negative electrode), while the chloride ions (Cl⁻) move towards the anode (positive electrode).

3. **Consider the Nature of the Cathode**:
- The cathode is made of mercury (Hg). Mercury is a unique electrode because it can form amalgams with certain metals, including sodium.

4. **Discharge of Ions at the Cathode**:
- At the cathode, the sodium ions (Na⁺) are discharged. However, instead of being deposited as solid sodium, they react with the mercury to form sodium amalgam (Na-Hg). This is because sodium is highly reactive and does not exist freely in the elemental state in the presence of water.

5. **Conclusion**:
- Therefore, during the electrolysis of NaCl solution with mercury as the cathode, the ions discharged at the cathode are sodium ions (Na⁺), which are discharged in the form of sodium amalgam.

### Final Answer:
The ions discharged at the cathode are sodium ions (Na⁺), which form sodium amalgam.

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