30. Solving a chemistry problem

1. A sample of semiconductor material weighing 0.1200 g was dissolved in 125 ml of acid and from 25 ml of this solution after appropriate treatment, 10 ml of a colored PbR solution was obtained. The colored compound is extracted with 2 ml of chloroform and the chloroform extract is photometered in a cuvette with a layer thickness of 2 cm. What molar absorption coefficient should the colored compound have so that the lead concentration in the semiconductor material does not exceed 1 * 10-5%, and the minimum optical density is 0.02?