The reaction of a hydrocarbon with oxygen to produce carbon dioxide and water is called

• A. Synthesis
• B. Combustion
• C. Decomposition
• D. Single-Replacement

Answer: (B)

Combustion is the type of reaction where a substance reacts with oxygen to release energy and form oxides. When a hydrocarbon burns in oxygen, its carbon and hydrogen are oxidized to carbon dioxide and water, typically releasing heat. That pattern—a hydrocarbon plus oxygen yielding carbon dioxide and water—defines complete combustion, which is the classic example of this reaction class (for example, CH4 + 2 O2 → CO2 + 2 H2O).

Synthesis would build a more complex compound from simpler ones, so it doesn’t describe burning. Decomposition splits a compound into simpler pieces, which isn’t what happens when a fuel reacts with oxygen. Single-replacement involves one element kicking another out of a compound, not a fuel reacting with oxygen to form oxides.