Utilizing pH to get concentrations

a. What is the concentration of a 75 ml solution of benzoic acid with a pH of 3.9? (pKa = 4.2)
b. If the current ocean pH is 8.1, what is the most likely ratio of H2CO3/HCO:-/CO32- present? pKai = 6.4; pKaz = 10.3
c. One proposed solution to ocean acidification is to, essentially, add a base back to the ocean. If we were to try to change the pH of the Atlantic Ocean (roughly 3 x 1020 L) to 8.2, how many grams of NaOH would we have to add if there is a 2.3 mM carbonic acid buffer current at a pH of 8.1? (Assume any volume change is negligible).

Which answer lists the fundamental forces in order from strongest to weakest

This element exists in adundance in the sun.explain how you would go about capturing sunlight.would this captured sunlight contain any of the element?

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.