é comum na agricultura a adição de húmus a um solo pouco produtivo, uma vez que esse composto traz muitos benefícios, tais como: retém a umidade do solo por mais tempo e promover a liberação de nutrientes lentamente. comente sobre como o húmus é formado

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.