On passing `CO_(2)` gas in excess in aqueous solution of sodium carbonate , the substance obtained is

Options

A. `NaOH`
B. `NaHCO_(3)`
C. `Na_(2)CO_(3).10H_(2)O`
D. `Na_(2)CO_(3).H_(2)O`

Explanation

To solve the question of what substance is obtained when carbon dioxide (CO₂) is passed in excess through an aqueous solution of sodium carbonate (Na₂CO₃), we can follow these steps:

### Step 1: Write the chemical equation for the reaction
When carbon dioxide is bubbled through an aqueous solution of sodium carbonate, a reaction occurs. The sodium carbonate reacts with carbon dioxide and water to form sodium bicarbonate (sodium hydrogen carbonate).

The reaction can be represented as:
\[ \text{Na}_2\text{CO}_3 (aq) + \text{CO}_2 (g) + \text{H}_2\text{O} (l) \rightarrow 2 \text{NaHCO}_3 (aq) \]

### Step 2: Identify the product
From the balanced equation, we can see that the product formed is sodium bicarbonate (NaHCO₃).

### Step 3: Analyze the options provided
Now, we can check the options given in the question:
1. NaOH (sodium hydroxide)
2. NaHCO₃ (sodium hydrogen carbonate)
3. Na₂CO₃ (sodium carbonate)
4. A variation of Na₂CO₃ with H₂O

From our reaction, we see that the correct product is indeed sodium hydrogen carbonate (NaHCO₃).

### Conclusion
Thus, the substance obtained when CO₂ is passed in excess through an aqueous solution of sodium carbonate is **sodium hydrogen carbonate (NaHCO₃)**.

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