Which reaction type involves breaking a single compound into simpler substances?

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

Answer: (B)

Breaking a single compound into simpler substances is a decomposition reaction. In this type, one reactant splits apart into two or more products as chemical bonds break, often requiring energy input such as heat or electricity. For example, heating calcium carbonate yields calcium oxide and carbon dioxide. This differs from synthesis, where multiple substances come together to form one compound; combustion, which involves rapid oxidation usually producing carbon dioxide and water; and double-replacement, where parts of two compounds trade partners to form new substances. So the described process fits decomposition because it starts with one substance and ends with simpler ones.