Which of the following is strong acid?

Explanation

The strength of an acid is influenced by the electronegativity of atoms attached to the carboxylic acid group. Fluorine is the most electronegative halogen, which increases the acidity of F₂CHCOOH due to its greater ability to stabilize the negative charge on the conjugate base. In contrast, iodine is the least electronegative, resulting in a weaker acid. Bromine and chlorine fall between fluorine and iodine in terms of electronegativity, making their corresponding acids of moderate strength.