All of the following, when mixed in stoichiometrically equal amounts, form a weakly basic solution except _______.
1) HClO₄(aq) + LiOH(aq) ⇌ LiClO4(aq) + H₂O(l)
2) H₂CO₃(aq) + Ca(OH)₂(aq) ⇌ CaCO₃(aq) + 2H₂O(l)
3) HCN(aq) + KOH(aq) ⇌ KCN(aq) + H₂O(l)
4) CH₃CO₂H(aq) + NaOH(aq) ⇌ NaCH₃CO₂(aq) + H₂O(l)