Which reaction involves a single substance breaking down into two or more substances?

Which reaction involves a single substance breaking down into two or more substances?

• A. Synthesis
• B. Decomposition
• C. Combustion
• D. Neutralization

Answer: (B)

Decomposition reactions involve a single compound breaking down into two or more substances. This happens when a compound is energized—by heat, electricity, or another trigger—causing its bonds to split and form simpler products. A classic example is calcium carbonate decomposing into calcium oxide and carbon dioxide: CaCO3 -> CaO + CO2. The other types don’t fit this pattern: synthesis is when two or more substances combine to form one product; combustion is burning with oxygen to produce heat and new substances like carbon dioxide and water; neutralization is an acid–base reaction forming a salt and water.

Decomposition reactions involve a single compound breaking down into two or more substances. This happens when a compound is energized—by heat, electricity, or another trigger—causing its bonds to split and form simpler products. A classic example is calcium carbonate decomposing into calcium oxide and carbon dioxide: CaCO3 -> CaO + CO2. The other types don’t fit this pattern: synthesis is when two or more substances combine to form one product; combustion is burning with oxygen to produce heat and new substances like carbon dioxide and water; neutralization is an acid–base reaction forming a salt and water.