Which of the following reveals a pattern observed by scientists?
a. hot springs are warmed year-round by melted rock.
b. a woman can get pregnant at a certain time each month.
c. mud sometimes smells like rotten eggs because of chemicals
inside the mud
d. waves on the ocean can be very tall.

Avariable that is not being directly tested during an experiment should be

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.

Select the correct lewis structure for fluorine which is group 7a element?