Which gas is responsible for the puffed - up appearance of dough?

Options

A. `CO_(2)`
B. `O_(2)`
C. `SO_(2)`
D. `NO_(2)`

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks about the gas responsible for the puffed-up appearance of dough, which is commonly used in baking and fermentation processes.

2. **Identifying the Process**: The puffed-up appearance of dough is primarily due to fermentation. During this process, microorganisms, particularly yeast, convert sugars into alcohol and carbon dioxide.

3. **Recognizing the Key Gas**: Among the gases produced during fermentation, the most significant one that contributes to the dough's rise is carbon dioxide (CO2).

4. **Relating to Specific Examples**: In baking, yeast such as Saccharomyces cerevisiae is commonly used. This yeast ferments the sugars present in the dough, producing carbon dioxide as a byproduct.

5. **Conclusion**: Therefore, the gas responsible for the puffed-up appearance of dough is carbon dioxide (CO2).

**Final Answer**: Carbon dioxide (CO2) is the gas responsible for the puffed-up appearance of dough.

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