Which pair of aqueous solutions, when mixed, will result in a precipitation reaction?

• A. LiBr(aq) and Na2CO3(aq)
• B. KNO3(aq) and Na2SO4(aq)
• C. NH4Cl(aq) and NaNO3(aq)
• D. NaCl(aq) and AgNO3(aq)

Answer: (D)

Verified step by step guidance

1. Identify the ions present in each solution. For example, NaCl(aq) contains Na\textsuperscript{+} and Cl\textsuperscript{-}, and AgNO3(aq) contains Ag\textsuperscript{+} and NO3\textsuperscript{-}.
2. Write down the possible combinations of cations and anions when the two solutions are mixed. For NaCl and AgNO3, the possible products are AgCl and NaNO3.
3. Check the solubility rules to determine if any of the possible products are insoluble in water. According to solubility rules, AgCl is insoluble and will precipitate, while NaNO3 is soluble.
4. Conclude that a precipitation reaction occurs if an insoluble salt forms. Since AgCl is insoluble, mixing NaCl and AgNO3 results in a precipitation reaction.
5. Apply the same process to the other pairs to confirm that no insoluble products form, thus no precipitation occurs with those pairs.