Which of the following correctly describes a compound? (4 points) a The atoms are chemically bonded together, and they retain their individual physical and chemical properties. b The atoms are not chemically bonded, and there is no set ratio for how the atoms can combine together. c The atoms can only combine in fixed ratios, and they can only be separated by a chemical change. d The atoms do not retain their individual chemical properties, and they can be separated by physical means.

Achef makes salad dressing by mixing oil, vinegar, and spices, as shown. which type of matter is the salad dressing?

Calcium chloride +gold(1) oxide—>

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.