Which compound, also referred to as a base, reacts with acids to form salts?

The term "alkali" refers specifically to a subset of bases that are soluble in water and can react with acids to form salts and water in a neutralization reaction. When an alkali is combined with an acid, such as hydrochloric acid, the result is the formation of a salt (like sodium chloride) and water. This reaction is fundamental in chemistry and is significant in various applications, including in cosmetology, where pH balance is crucial for product formulation and skin care.

The other options, although related to different chemical processes, do not define a compound that reacts with acids to form salts. Acids are compounds that donate protons and react with bases, while solvents are substances that dissolve solutes and do not necessarily fall into the acid/base category. A neutralizer could refer to a substance that balances pH but is not specifically defined as an alkali or base. Thus, alkali is the precise term that captures the definition of a base that reacts with acids to produce salts.