When you add sodium hydrogen carbonate to acetic acid in a test tube, a gas liberates immediately with a brick effervescence. Name this gas. Describe the method of testing this gas.

Explanation

**Step-by-Step Solution:**

1. **Identify the Reaction:**
When sodium hydrogen carbonate (NaHCO₃) is added to acetic acid (CH₃COOH), a chemical reaction occurs. The sodium hydrogen carbonate reacts with the acetic acid to produce sodium acetate (CH₃COONa), carbon dioxide (CO₂), and water (H₂O).

**Chemical Equation:**
\[
\text{NaHCO}_3 + \text{CH}_3\text{COOH} \rightarrow \text{CH}_3\text{COONa} + \text{CO}_2 + \text{H}_2\text{O}
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