1.which is not an example of the measure of the frequency of a wave?
a.
4 waves per second
b.
5 hertz
c.
2 cycles per second
d.
0.10 s per wave
2.which best describes what happens when a person sees a red leaf?
a.
the leaf radiates all colors of light except red to human eyes.
b.
human eyes reflect red light back to the leaf.
c.
the leaf absorbs red light from human eyes.
d.
red light reflected from the leaf enters human eyes.

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

Draw the lewis dot structure for each of the following polyatomic ions