On passing `CO_2` through a concentrated aqueous solution of `Na_2CO_3`, …………… is formed.

Explanation

To solve the question, we need to analyze the reaction that occurs when carbon dioxide (CO₂) is passed through a concentrated aqueous solution of sodium carbonate (Na₂CO₃).

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this scenario are carbon dioxide (CO₂) and sodium carbonate (Na₂CO₃).

2. **Understand the Reaction**:
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