135. Solving a chemistry problem

9. To prepare a reference solution, 0.258 g of lead nitrate was dissolved in 250 ml of water. After treatment of 5 ml of the solution with dithizone, 50 ml of a colored solution was obtained. The colored compound was extracted with 10 ml of chloroform, and the optical
the density of the chloroform layer was found to be 0.35. A weighed portion of the investigated alloy (1 g) was dissolved in acid and the solution was diluted with water to 100 ml. After treatment of 10 ml of this solution with dithizone, 25 ml of a colored solution was obtained. The colored compound was extracted with 10 ml of chloroform and the optical density of the chloroform layer in the same cuvette was 0.14. Determine the lead content in the alloy (in %).