The correct option is Salt and water.
Explanation
A neutralisation reaction is a specific type of chemical reaction in which an acid and a base react quantitatively with each other. In aqueous solutions, this reaction results in there being no excess of hydrogen or hydroxide ions present in the solution.
Detailed Analysis
The general chemical equation for a neutralisation reaction is represented as:
Acid + Base → Salt + Water
- Mechanism: The hydrogen ions ($H^+$) from the acid combine with the hydroxide ions ($OH^-$) from the base to form water ($H_2O$).
- Salt Formation: The remaining cation from the base and the anion from the acid combine to form an ionic compound known as a salt.
- Example: When Hydrochloric acid ($HCl$) reacts with Sodium hydroxide ($NaOH$), the products are Sodium chloride ($NaCl$) and Water ($H_2O$).
Equation: $HCl + NaOH \rightarrow NaCl + H_2O$
Options Acid and base, Gas and salt, and Hydrogen and oxygen are incorrect because they do not represent the standard products formed during the neutralisation process.
Key Takeaway: The fundamental products of a reaction between an Arrhenius acid and an Arrhenius base are always a salt and water, often accompanied by the release of heat (exothermic reaction).