Final answer:
Vinegar, which contains acetic acid (CH3COOH), is the acid among the options provided. Sodium hydroxide (NaOH) is a strong base, ammonia (NH3) is a weak base, and water (H2O) is neutral.
Step-by-step explanation:
The acid among the given choices is vinegar, which is an aqueous solution of acetic acid (CH3COOH). Sodium hydroxide (NaOH), also known as lye or caustic soda, is instead a strong base. When dissolved in water, NaOH dissociates completely into sodium (Na+) and hydroxide (OH-) ions, increasing the pH and thus is not an acid. Ammonia (NH3), another choice, is also known as a weak base, not an acid. It reacts with water to form small amounts of hydroxide ions (NH3(g) + H2O(l) = NH4+(aq) + OH-(aq)). Finally, water (H2O) is neutral, neither an acid nor a base.
Vinegar's characteristic smell comes from acetic acid, and it's commonly used in cooking and as a cleaning agent. The dissociation of acetic acid in water is represented by the equation CH3CO2H(aq) + H2O(aq) ⇒ H3O+(aq) + CH3CO2-(aq), where it donates a proton to water, forming hydronium ions (H3O+) and acetate ions (CH3CO2-), a typical behavior of acids.