Which definition describes an acid?

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Multiple Choice

Which definition describes an acid?

Acidity is defined by the ability to supply protons in solution. In water, acids donate H+ ions, which are immediately captured by water to form hydronium ions (H3O+). This increase in hydrogen ion concentration is what characterizes an acid in the usual aqueous sense. So a substance that produces H+ ions when dissolved in water best matches how acids are defined, because those protons become hydronium in the solution. For context, when a strong acid like HCl dissolves, it dissociates completely to yield H+ and Cl−, effectively increasing the H+ (or H3O+) concentration in the solution. We also call acids proton donors for this reason. Other options describe a base (donating hydroxide ions), or describe reactions or properties not defining acidity, such as neutralizing bases or releasing CO2 in water.

Acidity is defined by the ability to supply protons in solution. In water, acids donate H+ ions, which are immediately captured by water to form hydronium ions (H3O+). This increase in hydrogen ion concentration is what characterizes an acid in the usual aqueous sense. So a substance that produces H+ ions when dissolved in water best matches how acids are defined, because those protons become hydronium in the solution.

For context, when a strong acid like HCl dissolves, it dissociates completely to yield H+ and Cl−, effectively increasing the H+ (or H3O+) concentration in the solution. We also call acids proton donors for this reason. Other options describe a base (donating hydroxide ions), or describe reactions or properties not defining acidity, such as neutralizing bases or releasing CO2 in water.

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