At what pH, there are approximately equal amounts of H₂PO₄⁻ and HPO₄²⁻?

✅ Explanation:
This question relates to the concept of pKa (acid dissociation constant) and buffer systems. The pKa value for the second dissociation of phosphoric acid (H₂PO₄⁻ losing a proton to become HPO₄²⁻) is approximately 7.2. At a pH equal to the pKa, the concentrations of the acid (H₂PO₄⁻) and its conjugate base (HPO₄²⁻) are equal. This is a key principle in buffer solutions, where they resist changes in pH around their pKa value.