18. Aqueous Equilibrium

Which pairs of compounds are capable of making a buffer? Select all that apply.

a) 1.3 M LiOH and 1.7 M HCOOH                       c) 0.35 M CH₃CO₂H and 0.35 M NaOH

b) 0.784 M NH₄⁺ and 0.800 M HClO₄                  d) 0.80 HNO₃ and 0.15 MgO