To determine the mass percentage of sodium chloride NaCl in the original solution, we first need to find the moles of the precipitate formed, which is silver chloride AgCl .The balanced chemical equation for the reaction between sodium chloride and silver nitrate is:NaCl aq + AgNO aq AgCl s + NaNO aq From the equation, we can see that the mole ratio between NaCl and AgCl is 1:1.First, we need to find the moles of AgCl formed. The molar mass of AgCl is 107.87 g/mol for Ag + 35.45 g/mol for Cl = 143.32 g/mol.Moles of AgCl = mass of AgCl / molar mass of AgClMoles of AgCl = 2.655 g / 143.32 g/mol = 0.0185 molSince the mole ratio between NaCl and AgCl is 1:1, the moles of NaCl in the original solution is also 0.0185 mol.Now, we can find the mass of NaCl in the original solution. The molar mass of NaCl is 22.99 g/mol for Na + 35.45 g/mol for Cl = 58.44 g/mol.Mass of NaCl = moles of NaCl molar mass of NaClMass of NaCl = 0.0185 mol 58.44 g/mol = 1.080 gNow, we can find the mass percentage of NaCl in the original solution. The total mass of the solution is not given, so we will assume that the density of the solution is approximately equal to the density of water 1 g/mL since the concentration of NaCl is not very high. Therefore, the mass of the 25 mL solution is approximately 25 g.Mass percentage of NaCl = mass of NaCl / total mass of solution 100Mass percentage of NaCl = 1.080 g / 25 g 100 = 4.32%The mass percentage of sodium chloride in the original solution is approximately 4.32%.