A. A main group element with the valence electron configuration 4s2 is in periodic group ( ). It forms a monatomic ion with a charge of ( ). B. A main group element with the valence electron configuration 3s23p5 is in periodic group ( ). It forms a monatomic ion with a charge of ( ).

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.

How many moles are in 123.0 grams of kclo4?

What prefix multiplier is appropriate for reporting a measurement of 5.57 ×10−5 m?