Before a chemical reaction, the total mass of two reactants is measured to be 40 grams. After the reaction, what should be the total mass of the products?
A. 0 grams
B. 20 grams
C. 40 grams
D. 80 grams

Imagine that you own a property that is exactly 2.2 acres large. you want to sell your property, but your realtor tells you that you cannot sell your land by the acre. in order to sell your land you need to determine the area you own in units of square meters? given that there are 1.6 kilometers in 1 mile and 640 acres in 1 square mile, what is the area of land that you own in square meters square meters?

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

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.