What is the name of the reaction when an acid reacts with an alkali?

• A. Oxidation
• B. Precipitation
• C. Neutralisation
• D. Decomposition

Answer: (C)

Neutralisation is the reaction where an acid reacts with a base (an alkali in water) to form a salt and water. In solution, the acid provides hydrogen ions (H+), and the alkali provides hydroxide ions (OH−); they combine to make water, and the other ions pair up to form the salt. A classic example isHCl(aq) reacting with NaOH(aq) to give NaCl(aq) and H2O(l). This type of reaction is what neutralises acidity, moving the solution toward a neutral pH. Oxidation, precipitation, and decomposition describe different processes (electron transfer, solid formation from dissolved ions, and breaking a compound into simpler substances, respectively) and do not capture the acid–base neutralisation that produces salt and water.