The Common- Ion Effect Refers to the Observation _

Multiple Choice

The common- ion effect refers to the observation _ .

A) ions such as K⁺ and Na⁺ are common ions, so that their values in equilibrium constant expressions are always 1.00
B) that the selective precipitation of a metal ion, such as Ag⁺, is promoted by the addition of an appropriate counterion (X^- ) that produces a compound (AgX) with a very low solubility
C) that some ions, such as Na⁺ (aq) , frequently appear in solutions but do not participate in solubility equilibria
D) common ions, such as Na⁺ (aq) , don't affect equilibrium constants
E) that common ions precipitate all counter- ions