1011. Solving a chemistry problem

4. To determine bismuth in wastewater (in mg/l), a 10.0 ml sample of it was placed in a 50.0 ml volumetric flask, acidified with dilute nitric acid, a solution of bismuthol-1 (a reagent for bismuth) was added, and brought to the mark with water . The optical density of the resulting solution at λ = 440 nm in a cuvette with l = 2 cm turned out to be 0.150. The optical density of the standard solution obtained by treating 1.0 ml of a 10−4 M solution of Bi(NO3)3 • 5H2O under similar conditions is 0.2000. What is the content of bismuth in water? Does it exceed the maximum permissible concentration of 0.5000 mg/l?