A buffer solution can be formed by dissolving equal moles of which substances?

A buffer solution is designed to resist changes in pH when small amounts of acid or base are added. It typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid.

In the context of creating a buffer solution, the combination of hydrofluoric acid (HF), a weak acid, with sodium fluoride (NaF), the salt of the conjugate base (F⁻ ion), is particularly effective. When equal moles of HF and NaF are mixed, they establish an equilibrium that can absorb excess H⁺ ions or OH⁻ ions, thus maintaining a relatively constant pH.

HF partially dissociates in solution, providing the H⁺ ions, while NaF dissociates to provide the F⁻ ions. The presence of both components allows the solution to resist changes in pH effectively.

The other options do not form a buffer system. For instance, a strong acid like HCl paired with NaOH, a strong base, would neutralize each other rather than establishing a buffering system. Additionally, while KBr and Na3PO4 includes a salt and a phosphate species, it is not a combination of a weak acid and its conjugate base, leading to