During the combustion of a hydrocarbon, what happens to the atoms of the original substance?

• A. They remain unchanged and are released as free atoms.
• B. They are rearranged to form new molecules, typically carbon dioxide and water.
• C. They are destroyed and disappear from the system.
• D. They combine to form only elemental carbon and hydrogen gas.

Answer: (B)

Verified step by step guidance

1. Understand that in a chemical reaction, atoms are neither created nor destroyed; this is the Law of Conservation of Mass.
2. Recognize that during the combustion of a hydrocarbon, the atoms in the original molecule are rearranged rather than disappearing or remaining as free atoms.
3. Identify that the typical products of hydrocarbon combustion are carbon dioxide (CO\_2) and water (H\_2O), meaning carbon and hydrogen atoms combine with oxygen atoms from O\_2.
4. Note that the atoms from the hydrocarbon and oxygen molecules rearrange to form these new molecules, preserving the total number of each type of atom.
5. Conclude that the atoms are conserved and simply reorganized into new chemical species, not destroyed or left as free atoms.