The absorbance of a chlorophyll a standard solution in ethanol (density = 0.785 g/ml) is measured in
a 1.3 cm cuvette or path length. the absorbance is 0.765 and the molar absorptivity coefficient is 86,300 m–1cm–1.
the molecular weight for chlorophyll a is 893.49 g/mol.
what is the concentration of the solution in ppm?

Dying the folding patterns of protein molecules can microbiologists better understand cellular processes as well as some diseases, such as alzheimer’s, that are caused by proteins that have misfolded. the folding of these complicated molecules can be simulated on computers, but it takes a lot of processor power and time for even expensive supercomputers to do this. a group of researchers at stanford university developed software that can be used to distribute the processing of data to anyone who is willing to donate time on their idle personal computers. as a result, the researchers have been able to achieve protein-folding simulations that are far better than those other computing methods have done. which statement best describes the work of these researchers? the work is not scientific because the data are not processed in one location. the work is not scientific because the simulations are not reproducible. the researchers applied creativity to solve a problem in running an experiment. the researchers used only well-established scientific techniques.

To find the work done, the force exerted and distance moved are multiplied. a couch is moved twice before you are happy with its placement. the same force was used to move the couch both times. if more work is done the first time it is moved, what do you know about the distance it was moved? a) when more work was done, the couch was moved the same distance. b) when more work was done, the couch was moved less. c) when more work was done, the couch was moved further. d) when more work was done, the couch wasn't moved at all.

Apound is approximately 0.45 kilogram. a persons weighs 87 kilograms. what is the persons’s weight, in pounds, when expressed to the correct number of significant figures