In which type of combustion the fuel catches fire immediately.

Options

A. slow combustion
B. rapid combustion
C. explosion
D. mild reaction

Answer

**Step-by-Step Solution:**

1. **Understanding Combustion Types**: Combustion can be classified into different types based on how quickly the fuel burns. The main types are rapid combustion, slow combustion, explosion, and mild reaction.

2. **Defining Rapid Combustion**: Rapid combustion is a type of combustion where the fuel catches fire immediately and burns quickly. This process releases a significant amount of heat and light in a short period.

3. **Examples of Rapid Combustion**: A common example of rapid combustion is the burning of petroleum gas (LPG). When LPG is ignited, it catches fire almost instantly and burns rapidly.

4. **Comparison with Other Types**:
- **Slow Combustion**: This occurs at low temperatures and releases less heat over a longer period. An example is the burning of wood in a fireplace.
- **Explosion**: This is a sudden reaction that releases heat, light, and a large amount of gas. Firecrackers are a typical example of an explosive reaction.
- **Mild Reaction**: This type of reaction is not very strong and does not produce significant heat or light. Symptoms like skin rashes or runny noses can be associated with mild reactions.

5. **Conclusion**: Based on the definitions and examples, the type of combustion where the fuel catches fire immediately is **rapid combustion**.

**Final Answer**: Rapid combustion is the type of combustion where the fuel catches fire immediately.

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