Aqueous Solutions of Many Metal Cations Have a PH Different

Multiple Choice

Aqueous solutions of many metal cations have a pH different from 7. Which one of the following statements about these cations is not correct?

A) Alkali metal cations such as Na⁺ and K⁺ have a negligible effect on the pH.
B) Small and highly charged main group metals such as Al³⁺ produce acidic aqueous solutions.
C) For transition metal cations, the cation with the higher oxidation state produces the more acidic solution; for example, Fe³⁺(aq) is more acidic than Fe²⁺(aq) .
D) A solution containing Cr²⁺ is expected to be considerably more acidic than a solution of equal concentration containing Ni²⁺.
E) The Lewis acidity of a metal cation is a good measure of its ability to activate a water molecule to lose a proton and produce a hydronium ion.