145. Solving a chemistry problem

52. Option 2
After an appropriate treatment, 100.00 ml of solution was obtained from a sample of ore weighing m g containing niobium. In measuring cobels with a capacity of 25.00 ml were placed 2.00; 3.00 and 3.00 ml of the resulting solution and 1.00 ml of a standard containing 10.00 μg / ml niobium was added to a third flask. EDTA, tartaric and sulfuric acids, IREA lumogallion were added to each flask, heated to accelerate the complexation reaction, cooled and brought to the mark. The optical densities of the second (Aoth.2) and the third (Aot.3) solutions were measured relative to the solution in the first flask.
Calculate the mass fraction (%) of niobium in the ore for the following options:
Option 2
m = 0.1500 g
Aoth.2 = 0,310
Aoth.3 = 0,495