A conjugate acid is the species that a. remains after a base has given up a proton. b. is formed by the addition of a proton to a base. c. is formed by the addition of a proton to an acid. d. remains after an acid has given up a proton.

b.

Explanation:

A conjugate acid-base pair are related to each other through the addition or loss of a proton. Acids react by giving up a proton, and the resulting product of that reaction is the conjugate base. Thus, the conjugate base will have one proton less than the acid. Similarly, bases react by receiving protons, so the conjugate acid will have one proton more than the conjugate base that reacted.

In the following example, HA is the acid while A⁻ is the conjugate base:

HA + H₂O ⇒ H₃O⁺ + A⁻

Answer option a. and c. are not correct since bases to not give up protons and acids to not receive protons. Base on the above information, a conjugate base reacts to produce the conjugate acid and vice versa. Thus, to produce the conjugate acid, the conjugate base received a proton. The correct answer is b.