What does the symbol (aq) represent in a chemical equation?

The symbol (aq) in a chemical equation indicates that a substance is in an aqueous solution, meaning it is dissolved in water. When a solute is mixed with water to form a solution, the solute's molecules or ions become surrounded by water molecules, allowing it to disperse evenly throughout the solvent. This is commonly seen in reactions involving ionic compounds and acids, where the ions are separated and freely float in the water, making the solution conductive and enabling various chemical reactions to occur.

For example, when table salt (sodium chloride) is dissolved in water, it dissociates into its constituent ions (Na⁺ and Cl⁻), and you would represent this in a chemical equation as NaCl (aq). This notation is vital for accurately conveying reaction conditions and understanding the nature of the substances involved. Other options represent different physical states unrelated to the specific concept of a substance being dissolved in water.