Given that oxygen-16 and oxygen-18 both have an atomic number of 8, how many electrons, protons, and neutrons do these oxygen atoms contain? a. both oxygen isotopes contain 8 electrons and 8 protons but each contains a different number of neutrons - 8 and 10 respectively. b. the oxygen isotopes contain 8 electrons but each contains a different number of neutrons and protons - 8 and 10 respectively. c. these oxygen configurations contain the same number of subatomic particles - 8 electrons, 6 protons and 10 neutrons. d. any oxygen atom contains 8 electrons and 9 neutrons but these vary in the number of protons - 8 and 10 respectively.

What are the primary responsibilities of a chemical engineer involved in "r& d"? develop large scale manufacturing operations discover new products and processes training of new chemists determine products needed by consumers

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.

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.