53 (3). To construct a calibration graph, 5.00 8.00 10.

53 (3). To construct a calibration graph, 5.00 8.00 10.00 ml of a solution of iron ammonium alum with T (Fe) = 0.0000500 were placed in flasks with a capacity of 50.00 ml, hydrochloric acid was added to potassium thiocyanate, brought to the mark with water, and optical density was measured at 495 nm:
Y, ml 5.00 8.00 10.00
A, 0.365 0.595 0.750
The test solution containing iron and nickel was diluted in a flask with a capacity of 100.00 ml, two aliquots of 20.00 ml were taken into flasks with a capacity of 50.00 ml. One sample was diluted to the mark with water. The optical density of the first sample at 495 nm is А Ni = 0.060. Optical densities of the second sample are equal for different variants.
Option 3
0.660