Which of the following is NOT a characteristic of acids?

The correct answer is that acids do not release hydroxide ions in solution. Instead, acids are defined by their ability to release hydrogen ions (H⁺) when dissolved in water. The characteristic of releasing hydroxide ions is fundamentally associated with bases, not acids.

Acids exhibit several distinct properties: they taste sour, which is a typical sensory characteristic of substances like citric acid or acetic acid. In addition, acids can change the color of litmus paper; they will specifically turn blue litmus paper red, indicating their acidic nature. Moreover, many acids can react with metals, sometimes producing hydrogen gas in the process, which is notable in reactions with reactive metals like zinc or magnesium.

Hence, the identification of the release of hydroxide ions as a characteristic of acids is inaccurate and clarifies why this option stands out as not fitting within the traits of acids.