De los siguientes conjuntos indique con una cruz los que constituyen un sistema material drogas en un botiquín solución de sulfato de cobre en agua para verificar su cristalización alcohol para desinfectar una herida hielo, vaso de precipitados, termómetro para determinar su punto de fusión. Ayuda urgente pliss

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.