In Castner-Kellner cell, sodium ions react with mercury to form `"___________"`

Explanation

To solve the question regarding what sodium ions react with mercury to form in the Castner-Kellner cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Castner-Kellner Cell**:
- The Castner-Kellner cell is used for the electrolysis of brine (aqueous sodium chloride solution) to produce sodium hydroxide (NaOH).

2. **Identifying the Components**:
...