An artifact originally had 16 grams of carbon-14 present. the decay model upper a equals 16 e superscript negative 0.000121 ta=16e−0.000121t describes the amount of carbon-14 present after t years. use the model to determine how many grams of carbon-14 will be present in 90769076 years.

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.