The acid used in a soda-aicd fire extinguisher ______ .

Options

A. Nitric acid
B. Carbon dioxide
C. Sulphuric acid
D. Nitrogen dioxide

Answer

To answer the question about the acid used in a soda-acid fire extinguisher, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components**: A soda-acid fire extinguisher typically consists of sodium bicarbonate (baking soda) and an acid. The purpose of the acid is to react with the baking soda to produce carbon dioxide gas.

2. **Identify the Acid**: The acid commonly used in soda-acid fire extinguishers is sulfuric acid (H₂SO₄). This acid reacts with sodium bicarbonate (NaHCO₃) to produce carbon dioxide (CO₂), which helps to smother the fire.

3. **Chemical Reaction**: The reaction can be represented as follows:
\[ \text{NaHCO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{CO}_2 \]
Here, sodium bicarbonate reacts with sulfuric acid to produce sodium sulfate, water, and carbon dioxide.

4. **Conclusion**: Therefore, the acid used in a soda-acid fire extinguisher is sulfuric acid.

### Final Answer:
The acid used in a soda-acid fire extinguisher is **sulfuric acid**.

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