Chemistry Regents Practice Test 2026 - Free Chemistry Regents Practice Questions and Study Guide

The reaction described, A + B → AB, is classified as a synthesis reaction. This type of reaction occurs when two or more reactants combine to form a single product. In this case, the individual substances A and B are joining together to create a new substance, AB.

Synthesis reactions are characterized by the formation of a more complex compound from simpler reactants, which perfectly aligns with the reaction presented. The other types of reactions mentioned differ in their processes: decomposition involves the breakdown of a compound into simpler products; single replacement involves one element replacing another in a compound; and double replacement involves the exchange of ions between two compounds. Thus, the combination of reactants A and B into a single product, AB, clearly defines the reaction as a synthesis reaction.