Final answer:
Out of the provided options, the combination of MgCl₂ and Pb(NO₃)₂ will form a precipitate. The resulting precipitate is lead(II) chloride (PbCl₂), which is insoluble in water.c) MgCl₂ + Pb(NO₃)2
Step-by-step explanation:
The question asked is about predicting whether a precipitate will form when two aqueous solutions are mixed. Specifically, we need to identify among the given pairs which will result in a precipitate. To determine this, we consider the solubility rules and check if any combination of cations and anions from the solutions form an insoluble compound.
Out of the given options, MgCl₂ + Pb(NO₃)₂ will form a precipitate when mixed, because lead(II) chloride (PbCl₂) is generally insoluble in water. The reaction is as follows:
MgCl₂ (aq) + Pb(NO₃)₂ (aq) → PbCl₂ (s) ↓ + Mg(NO₃)₂ (aq)
In this reaction, the ions Pb²⁺ and Cl⁻ combine to form the insoluble precipitate PbCl₂.
The other options, such as KNO₃ + HNO₃ and NaNO₃ + HCl, will not form a precipitate because all the products of their possible reactions are soluble in water. Additionally, HCl + NaOH will result in a neutralization reaction producing water and a soluble salt, so no precipitate will form there either.