Antimony (Sb) has two stable isotopes. 121Sb has a mass of 120.90 amu. 123Sb has a mass of 122.90 amu. Answer the following questions on a separate
piece of paper and upload the document.
a. Write an equation to describe the relationship between the percent
abundance of 121Sb and the percent abundance of 123Sb. Assume that no
other isotopes exist.
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b. Write an equation that you can use to calculate the percent abundance of
each isotope.
c. What is antimony's atomic mass? Use the periodic table.
d. Calculate the percent abundance for each isotope of antimony.

1. baking powder is a 1: 1 molar mixture of cream of tartar (khc4h4o6) and baking soda (nahco3). a recipe calls for two teaspoons (a total of 8.0 grams) of cream of tartar. how much baking soda must be added for both materials to react completely?

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.

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.