When all the molecules of a compound break apart in water to produce hydrogen ions, the compound is a ______ acid.

• A. Weak acid
• B. Strong acid
• C. Moderate acid
• D. Conjugate acid

Answer: (B)

Dissociation in water determines acid strength: when every molecule of an acid splits apart to give hydrogen ions, the solution reflects a complete release of protons. That behavior is the hallmark of a strong acid, because the equilibrium lies far to the right and the Ka is large. So the statement describes a strong acid. In contrast, a weak acid only partly dissociates, so not all molecules release H+, and the equilibrium sits more toward the undissociated form with a smaller Ka. The term conjugate acid refers to the species formed when a base has accepted a proton, not to how completely an acid dissociates, so it doesn’t define the described behavior.