50. Solving a chemistry problem

274. To determine the content of Cu(II) in the presence of Fe(III), copper was previously separated on a cation exchanger in the H+ form. 5 ml of the test solution was added to the chromatographic column. To extract copper, the column was washed with a 0.5 M HCl solution and the solution was placed in a 250 ml volumetric flask. 25 ml of the resulting solution was taken and added to a volumetric flask with a capacity of 50 ml, 15 ml of 25% ammonia was added, brought to the mark with water, and the optical density was measured. To build a calibration graph, 2.0 was placed in volumetric flasks with a capacity of 50 ml; 5.0; 10.0; 15.0 ml of copper sulfate solution with a copper titer of 1. 10-3 g / ml, 15 ml of 25% ammonia was added, brought to the mark with water and the optical density of standard solutions was measured:
V, ml 2.0 5.0 10.0 15.0
Ast 0.05 0.15 0.30 0.45
Determine the concentration (mg/ml) of copper in the analyzed solution for the following options:
task number 274
Ah 0.27