HESI A2 Chemistry Practice Test

During a decomposition reaction, a compound undergoes a transformation where it breaks down into two or more simpler substances. This process typically occurs when a compound is subjected to heat, light, or an electrical current, leading to the separation of the compound into its constituent elements or simpler compounds.

For example, the decomposition of water (H2O) into hydrogen (H2) and oxygen (O2) gas can occur through electrolysis, where an electrical current is applied to the water, causing it to decompose. This reaction is essential in various chemical processes and helps establish the foundational principles of chemical reactions.

The other options do not describe decomposition reactions. Losing electrons is characteristic of oxidation reactions, combining substances describes synthesis reactions, and absorption of heat is related to endothermic reactions but doesn't specifically define decomposition. Therefore, the selection highlighting the breakdown into simpler substances accurately represents the nature of a decomposition reaction.