96. To construct a calibration graph for the determinat

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96. To construct a calibration graph for the determination of manganese, a 0.0001 M solution of manganese salt was used, an aliquot of which was diluted with a buffer solution to 25 ml and the following data were polarographed:
V, ml 1 2 3 4 5 6
h, 9 16 26.5 35 41 54
A 0.5 g mass of manganese-containing alloy was dissolved in 100 ml of nitric acid, 5 ml of the resulting solution was taken and it was diluted with the same buffer solution to 25 ml. By polarography, a wave height of 32.5 mm was obtained. Calculate the mass fraction of manganese in the alloy.