Answer:
HClO/NaClO
Explanation:
HClO; Kₐ = 3.2 × 10⁻⁸
HNO₃; Kₐ = large
CH₃COOH; Kₐ = 2 × 10⁻⁵
The most effective buffer will contain an acid with a pKₐ close the desired pH.
The buffer pair HClO/NaClO is the closest match.
pH = pKₐ = -log (3.2 × 10⁻⁸) = 7.49.
HNO₃/NaNO₃ will give pH ≈ 1
CH₃COOH/CH₃COONa will give a pH closer to 4.7
