Final answer:
The set of chemicals HClO2 & ClO2− is an acid-base conjugate pair, where HClO2 is the conjugate acid and ClO2− is the conjugate base.
Step-by-step explanation:
The question asks which set of chemicals is an acid-base conjugate pair. A conjugate acid-base pair consists of two species that can transform into each other by the loss or gain of a proton (H+). According to the Brønsted-Lowry acid-base theory, the conjugate acid is the species that donates a hydrogen ion in the forward reaction, and the conjugate base is the species that accepts a hydrogen ion in the reverse reaction.
Looking at the options given, we can identify HClO2 & ClO2− as a conjugate acid-base pair. HClO2 can donate a proton to become ClO2−, making HClO2 the conjugate acid and ClO2− the conjugate base. This matches the definition of a conjugate acid-base pair where a conjugate acid (HClO2) loses a proton to form its conjugate base (ClO2−).