4. For the luminescent determination of aluminum in brass, weighed portion a was dissolved and, after appropriate treatment, the volume of the solution was adjusted to 500.0 ml. Then 10.0 ml of the solution was transferred into a 100 ml flask, a solution of acid chromium-blue-black was added and the volume was brought to the mark. The luminescence intensity of the resulting solution turned out to be Ix.
The intensity of the four standard solutions containing 100 ml 10.0; 20.0; 30.0 and 40.0 μg of aluminum, equal to 60; 82; 104 and 126 respectively. Build a calibration graph and determine the percentage of aluminum in brass for the following options:

Options 4
m, g 0.1500
Ix 0.91

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