Chemistry 5070 · O Level · Physical and chemical changes

Physical and chemical changes — practice question

Octane, $\text{C}_8\text{H}_{18}$, belongs to the hydrocarbon family. When octane is combined with an excess of oxygen, nothing happens unless energy is added. Once energy is added, either as heat or an electric spark, the change occurs rapidly. The products formed in this change include carbon dioxide. Which detail in this description indicates that the change is a chemical change?

  • AOctane is a hydrocarbon.
  • BNo change takes place unless energy is supplied.
  • CThe change takes place quickly.
  • DCarbon dioxide is produced.

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