define water gas?

Explanation

**Step-by-Step Solution:**

1. **Definition of Water Gas**: Water gas is a type of gas fuel that is primarily composed of two gases: carbon monoxide (CO) and hydrogen (H2).

2. **Formation Process**: Water gas is produced by passing steam (H2O) over incandescent coke (a form of carbon).

3. **Chemical Reaction**: The chemical reaction that occurs during the formation of water gas can be represented as follows:
\[ \text{H}_2\text{O} + \text{C} \rightarrow \text{CO} + \text{H}_2 \]
Here, water (steam) reacts with carbon (from coke) to produce carbon monoxide and hydrogen.

4. **Composition of Water Gas**: The resulting mixture of carbon monoxide and hydrogen is what we refer to as water gas.

5. **Usage**: Water gas is used as a fuel gas and has applications in various industrial processes.

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