Why is it important to remove nitrogen and phosphorus from raw sewage?

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.

What type(s) of intermolecular forces are expected between ch3ch2cooh molecules? dipole forces, induced dipole forces, hydrogen bonding

Find the mass, in grams, of 5.00*10^23 molecules of f2