Final answer:
When a solution of C2 is mixed with one containing A- ions, and C2 represents a copper ion, the resulting solution's color typically changes to blue.
Step-by-step explanation:
When a solution of C2 is mixed with one containing A- ions, the result depends on the specific chemicals involved. However, based on the information provided, if we use FIGURE 19.37 as a reference, particularly in the case of [Cu(NH3)4]²+ ions, we understand that the color of a solution changes when certain ions absorb or transmit light of specific colors. In the provided case for copper ions in solution, they absorb red and orange light, resulting in the transmitted light appearing as the complementary color, which is blue. Therefore, if C2 represents a copper ion and A- represents an ion that would not alter the copper ion's typical behavior, then the solution would change to blue upon mixing.