Final answer:
Based on the information given, the least abundant ion in water is K⁺ (potassium ion). The solubility of AgCl in a 1.0 M KCl solution is greater than that in pure water due to the formation of other chloride-containing complexes.
Step-by-step explanation:
The least abundant ion in water is K⁺ (potassium ion). Based on the information given, if the common ion effect were the only important factor, we would predict that AgCl is approximately five orders of magnitude less soluble in a 1.0 M KCl solution than in water. However, the measured solubility of AgCl in 1.0 M KCl is almost a factor of 10 greater than that in pure water, largely due to the formation of other chloride-containing complexes.
The least abundant ion in water between potassium ion (K+) and chloride ion (Cl-) is potassium ion (K+) since it has a lower mass of 0.0005g compared to 0.004g of chloride ion.
The student question asks, What is the least abundant ion in water? The options given are A. K⁺ (potassium ion, 0.0005g) and B. Cl⁻ (chloride ion, 0.004 g). To determine the least abundant ion, we compare the given amounts of each ion in grams. Based on the provided data, potassium ion (K+) at 0.0005g is less abundant than chloride ion (Cl-) at 0.004g.