In the reaction mg(s) + 2hcl(aq) → h2(g) + mgcl2(aq), how many moles of hydrogen gas will be produced from 250.0 milliliters of a 3.0 m hcl in an excess of mg? 0.75 moles 0.38 moles 3.0 moles 1.5 moles

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.