How does it? Please help

What is the empirical formula for c4h8o2

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.

How does blood clotting prevent the entry of pathogens through cuts and wounds? answer asap,, this is due tomorrow. will mark as brainliest or whatever you call it : )