Humber Admissions Practice Test

In what type of reaction is the release of energy in the form of light significant?

1. Synthesis Reaction

2. Combustion Reaction

3. Decomposition Reaction

4. Redox Reaction

The correct answer is: Combustion Reaction

The correct choice captures the essence of combustion reactions, which are characterized by the significant release of energy, often in the form of heat and light. In a combustion reaction, a substance (typically a hydrocarbon) reacts rapidly with oxygen, resulting in the formation of carbon dioxide and water, along with the release of energy. This energy release is prominently observed as the heat and light produced during processes like burning fuels, making combustion reactions distinctly associated with visible energy output. Synthesis reactions, on the other hand, involve the combination of two or more reactants to form a single product, typically not yielding a substantial release of energy in the form of light. Decomposition reactions involve breaking down a compound into its constituents, which may not necessarily produce light or noticeable energy changes. Redox reactions involve the transfer of electrons between molecules, and while they can release energy, they don't inherently produce light as a significant byproduct like combustion does. Thus, combustion reactions stand out for their characteristic and notable energy release, particularly as light.