Which of the following aqueous solutions will have the highest pH?(a) NaCl(b) CH3COONa(c) Na2CO3(d) NH4Cl

To determine which of the given aqueous solutions will have the highest pH, we need to consider the nature of the ions present in each solution.

(a) NaCl: NaCl is a salt that dissociates into Na+ and Cl- ions in water. Neither of these ions will significantly affect the pH of the solution. Therefore, NaCl will not have a significant impact on the pH.

(b) CH3COONa: CH3COONa is the sodium salt of acetic acid. When dissolved in water, it dissociates into Na+ and CH3COO- ions. The CH3COO- ion is the conjugate base of acetic acid, which is a weak acid. The presence of this weak base will slightly increase the pH of the solution compared to pure water.

(c) Na2CO3: Na2CO3 is the sodium salt of carbonic acid. When dissolved in water, it dissociates into Na+ and CO3^2- ions. The CO3^2- ion is the conjugate base of carbonic acid, which is a weak acid. The presence of this weak base will increase the pH of the solution more than CH3COONa.

(d) NH4Cl: NH4Cl is the ammonium salt of hydrochloric acid. When dissolved in water, it dissociates into NH4+ and Cl- ions. The NH4+ ion is the conjugate acid of ammonia, which is a weak base. The presence of this weak acid will slightly decrease the pH of the solution compared to pure water.

Based on this analysis, the solution with the highest pH will be (c) Na2CO3, as it contains the strongest base among the given options.