Silver nitrate was added to sodium chloride 40 g with 20% salt content, what is the mass of the precipitate.

NaCl + AgNO3 = AgCl + NaNO3
Let’s find the mass of sodium chloride contained in a 20% solution.
m (NaCl) = 40 * 0.2 = 8 g
The goal of the problem is to calculate the mass of the sediment formed in this reaction. The precipitate is AgCl.
To do this, calculate the amount of NaCl mol.
n (NaCl) = m / M = 8 / 58.4 = 0.14 mol
According to the reaction equation n (NaCl) = n (AgCl) = 0.14 mol
Let’s find the mass of silver chloride.
m (AgCl) = n (AgCl) * M (AgCl) = 0.14 * 143.3 = 20 g
This solution is correct if an excess of AgNO3 solution was added to the NaCl solution (not indicated in the condition).