Final answer:
The correct answer is A) HCl / Cl⁻. This is not a conjugate acid-base pair because HCl is an acid and Cl⁻ is its conjugate base.
Step-by-step explanation:
The correct answer is A) HCl / Cl⁻. This is not a conjugate acid-base pair because HCl is an acid and Cl⁻ is its conjugate base. In a conjugate acid-base pair, the acid and its conjugate base differ by the gain or loss of a proton. In this case, HCl loses a proton to become Cl⁻, so they are not a conjugate pair.