O Which statement describes the appearance of a
temperature-vs.-time graph?
O A horizontal line shows that the temperature
increases at a constant rate over time.
A vertical line shows that the temperature
decreases at a constant rate over time.
O Horizontal lines where the temperature is
constant during phase changes connect
upward-sloping lines where the temperature
increases.
O Horizontal lines where the temperature
increases are connected by upward-sloping
lines where the temperature is constant for
each phase.

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.