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The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

Explain in detail of the four major scientific developments that spurred the formulation of the plate tectonics theory

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control?