What is a natural resource used to make polypropylene? a. the cracking process b. crude oil c. automobile parts d. plastic

Compare the valence electron configuration of the nobles gas elements seen here. what statement is correct?

How are evaporation and sublimation similar? a both involve the formation of a gas. b both release energy to the surroundings. c both take place throughout a solid. d both take place at the surface of a liquid.

Tooth enamel consists mainly of the mineral calcium hydroxyapatite, ca_10(po_4)_6(oh)_2. trace elements in teeth of archaeological specimens provide anthropologist with clues about diet and diseases of ancient people. students at hamline university measured strontium in enamel from extracted wisdom teeth by atomic absorption spectroscopy. solutions with a constant total volume of 10.0 ml contained 0.726 mg of dissolved tooth enamel plus variable concentrations of added sr. added sr find the concentration of sr in the 10 ml sample solution in parts per billion = ng/ml. find the concentration of sr in tooth enamel in parts per million = mu g/g.