A) Hydrochloric acid (HCl)
B) Sulfuric acid (H2SO4)
C) Acetic acid (CH3COOH)
D) Nitric acid (HNO3)
Answer: C) Acetic acid (CH3COOH)
Acetic acid (CH3COOH) is a weak acid. A weak acid is an acid that does not completely dissociate into ions in a solution. When acetic acid dissolves in water, it releases some of its hydrogen ions (H+), but not all of them. This results in a partial ionization. In contrast, strong acids like hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3) fully dissociate in water, releasing all of their hydrogen ions. This complete ionization makes them strong acids.
In the case of acetic acid, the equilibrium between the unionized and ionized forms of the acid lies more toward the unionized form, making it a weak acid. This property is why acetic acid is found in vinegar, giving it its characteristic sour taste but without the corrosive properties of strong acids like hydrochloric or sulfuric acid.