Which of the following is NOT a strong acid?

Ethanoic acid is considered a weak acid because it does not completely dissociate in water. In contrast, strong acids, such as nitric acid, hydrochloric acid, and sulfuric acid, fully dissociate into their respective ions when dissolved in water. This complete dissociation results in a high concentration of hydrogen ions (H⁺) in solution, which is a characteristic of strong acids.

Ethanoic acid, commonly known as acetic acid, partially ionizes in aqueous solutions, meaning that at any given moment, a significant number of ethanoic acid molecules remain undissociated. This is why it exhibits weaker acidic properties compared to the strong acids listed in the other options. Understanding the degree of dissociation is key in differentiating between strong and weak acids in chemistry.