An organic compound B has the molecular formula `C_2H_4O_2`. It reacts with sodium hydrogen carbonate to produce a gas and salt, the gas turns lime water milky.
Write its structural formula.

Explanation

To solve the problem step by step, we will analyze the given information about the organic compound B with the molecular formula C₂H₄O₂.

### Step 1: Identify the Compound
The molecular formula C₂H₄O₂ suggests that the compound could be an acid. Given that it reacts with sodium hydrogen carbonate (NaHCO₃) to produce a gas, we can infer that it is likely an acid.

### Step 2: Reaction with Sodium Hydrogen Carbonate
When an acid reacts with sodium hydrogen carbonate, it produces a salt, water, and carbon dioxide gas. The general reaction can be represented as:
\[ \text{Acid} + \text{Sodium Hydrogen Carbonate} \rightarrow \text{Salt} + \text{Water} + \text{Carbon Dioxide} \]
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