When a sodium (Na) atom forms an ion so that it looks like a noble gas with a full valence shell, what will its charge be? 2-
1-
3-
2+
1+
3+

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

Iwould appreciate if someone could me.

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.