How many moles are 4.20 x 1025 atoms of Ca?

Chen drew a diagram to compare the ways in which different organisms obtain nitrogen. which label belongs to the area marked z?

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.

The diagrams to the right show the distribution and arrangement of gas particles in two different containers. according to kinetic-molecular theory, which of the following statements is true? check all that apply. if the temperatures of both containers are equal, container a has greater pressure than container b. if the volume of container a decreased, its pressure would decrease. if the pressure in both containers is equal, container a has a lower temperature than container b.