Final answer:
HCl(aq) and Pb(NO3)2(aq) will produce a precipitate when mixed, due to the formation of insoluble lead(II) chloride (PbCl2). a.HCl(aq) and Pb(NO3)2(aq)
Step-by-step explanation:
To determine which pair of reactants will produce a precipitate when mixed together, we need to consider the solubility rules for ionic compounds in water. A precipitate will form when an insoluble substance is produced in the reaction. Looking at the options provided, Pb(NO3)2 paired with HCl(aq) will result in the formation of a precipitate. When these two react, they form soluble nitrate ions (NO3-) and lead(II) chloride (PbCl2), which is insoluble and will precipitate out of the solution.
The balanced equation for this reaction is:
Pb(NO3)2(aq) + 2 HCl(aq) → 2 HNO3(aq) + PbCl2(s)
Thus, the correct answer is a.HCl(aq) and Pb(NO3)2(aq).