Which statement best describes complete combustion?

Which statement best describes complete combustion?

• A. Carbon dioxide and water are produced, releasing energy.
• B. Carbon monoxide and water are produced, releasing energy.
• C. Carbon and water are produced, releasing energy.
• D. Carbon dioxide and methane are produced, releasing energy.

Answer: (A)

Complete combustion happens when there is plenty of oxygen for the fuel to burn fully, converting carbon to carbon dioxide and hydrogen to water, and the reaction releases energy as heat. That’s exactly what is described by producing carbon dioxide and water and releasing energy. If oxygen is limited, incomplete combustion can occur, giving carbon monoxide or even carbon (soot) along with water, and usually less energy is released. The other statements don’t fit complete combustion: carbon monoxide or solid carbon would indicate incomplete burning, and producing methane as a product isn’t how combustion proceeds. A simple example is methane burning: CH4 + 2O2 → CO2 + 2H2O, which shows the two main products and energy release.

Complete combustion happens when there is plenty of oxygen for the fuel to burn fully, converting carbon to carbon dioxide and hydrogen to water, and the reaction releases energy as heat. That’s exactly what is described by producing carbon dioxide and water and releasing energy. If oxygen is limited, incomplete combustion can occur, giving carbon monoxide or even carbon (soot) along with water, and usually less energy is released. The other statements don’t fit complete combustion: carbon monoxide or solid carbon would indicate incomplete burning, and producing methane as a product isn’t how combustion proceeds. A simple example is methane burning: CH4 + 2O2 → CO2 + 2H2O, which shows the two main products and energy release.