To use Charles' Law, which of the following needs to remain constant? A. Temperature and volume
B. Temperature and the number of moles of a gas
C. Pressure and volume
D. Pressure and temperature E. Pressure and the number of moles of a gas

Chemistry worksheet - i am not sure what they are asking for exactly?

The biosphere of the earth is made up of what compound? organic or inorganic?

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.