Calculate the empirical formulas of the following polymers: a.) PVC; 38.44% C, 4.84% H, 56.73% Cl
b.) Lucite; 59.98% C, 8.05% H, 31.96% O
c.) polyethylene; 85.63% C, 14.37% H
d.) polystyrene; 92.26% C, 7.74% H
e.) Orlon; 67.90% C, 5.70% H, 26.40% N

If we compare and contrast electromagnetic waves with sound waves, all but one statement is true. that is a) sound waves require a medium to travel while electromagnetic waves do not. b) electromagnetic waves can travel through the vacuum of space while sound waves cannot. c) electromagnetic waves must have a medium in which to travel, but sound waves can travel anywhere. eliminate d) sound waves must bounce off of matter in order to travel while electromagnetic waves do not require matter to be present.

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 point along a planet's orbit where it is closest to the sun is called the