OHST Practice Exam

Which of the following is one of the four necessary components for combustion to occur?

1. Oxygen

2. Fuel

3. Heat

4. Self-sustained chemical reaction

The correct answer is: Self-sustained chemical reaction

The correct answer is that one of the four necessary components for combustion to occur is heat. In the context of combustion, heat is essential because it provides the initial energy required to raise the fuel to its ignition temperature, allowing the chemical reaction with oxygen to commence. For combustion to take place, a fuel must be present, and it needs to be mixed with an oxidizer (usually oxygen) in the right proportions. Once the mixture reaches a certain temperature, a reaction occurs. This process generates heat, light, and various combustion products. Heat also sustains the reaction; as long as sufficient heat remains, the combustion can continue. The notion of a self-sustained chemical reaction is relevant, as combustion can produce enough heat to keep the reaction ongoing after it has started, but it is not one of the key components required for the ignition process itself. Thus, while a self-sustained reaction is a characteristic of combustion once initiated, heat is fundamental to initiating the reaction.