In a neutralization reaction, which two substances combine?

In a neutralization reaction, an acid and a base combine to form water and a salt. This process is characterized by the interaction between the hydrogen ions (H⁺) from the acid and the hydroxide ions (OH⁻) from the base, which leads to the formation of water (H₂O). The remaining components of the acid and base then combine to create a salt, which is an ionic compound.

This reaction is fundamental in chemistry as it essentially demonstrates how acids and bases can neutralize each other, resulting in a solution that is less acidic or basic compared to the original reactants. Other pairings mentioned in the choices, such as acid with metal or base with metal, do not represent neutralization reactions. They involve different types of chemical reactions where metals can react with acids to displace hydrogen or with bases under specific conditions. Thus, the correct answer emphasizes the classic concept of neutralization involving acids and bases.