52. Solving a chemistry problem

2. To determine nickel with dimethylglyoxime, dissolve a steel sample and dilute the solution to 100.0 ml. Add the required reagents to 5.00 ml of the solution, dilute with water to 50.00 ml and carry out photometrization at l = 1.0 cm, λeff = 470 nm (ε = 1.30 x 104). The optimal value of optical density is 0.435. If the mass fraction of nickel in the steel is about 1.0%, calculate the mass of the steel sample required for analysis.