AFOQT Practice Test

What happens during a decomposition reaction?

1. Two or more reactants combine

2. One element replaces another in a compound

3. A single compound breaks down into simpler substances

4. A substance releases energy upon reacting with oxygen

The correct answer is: A single compound breaks down into simpler substances

During a decomposition reaction, a single compound undergoes a process where it breaks down into simpler substances or individual elements. This reaction typically involves the breakdown of a chemical compound into two or more products, which can be elements or simpler compounds. Decomposition reactions often require energy input, such as heat, light, or electricity, to initiate the breakdown process. This understanding differentiates it from other types of reactions. For instance, the first option describes a combination reaction, where two or more reactants come together to form a more complex compound. The second option refers to a single replacement reaction, where one element in a compound is replaced by another element. The fourth option involves combustion reactions, in which a substance reacts with oxygen, often releasing energy. Therefore, identifying that a decomposition reaction specifically involves the breakdown of a compound into simpler components is key to understanding the correct answer.