Answer: 1:2.
Explanation:
It is a stichiometric problem,
from the equation: Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
The stichiometry of this reaction shows that 1.0 mol of lead nitrate reacts with 2.0 moles of KI to produce 1.0 mole of lead iodide and 2.0 moles of potassium nitrate.
Thus, the mole ratio of lead nitrate to potassium iodide is 1:2.
