e this article to answer questions about mass spectro ed to identify lead isotopes in the air around Mexico City. (25 points) etermination of Particulate Lead Using Aerosol Mass Spectrometry: MILAGRO/MCMA-2006 Observations 1. What were some purposes of the investigation? 3. One problem the researchers faced was an uncertainty about whether the signals observed in certain mass spectrometry data were, in fact, due to lead isotopes. Explain why this was a problem. In other words, why wasn't information about the mass of the isotopes sufficient for identifying the isotopes? Provide an example to explain your answer. 5. Analyze the graph in Figure 4 of the article. Describe the vertical and horizon axes, and explain how the isotopes are identified by the graph and what the heights of the curves mean. 6. Figure 11 in the article shows a way that researchers used data they obtained from mass spectrometry. Summarize the information about lead isotopes contained in each graph. Explain what conclusions the researchers could draw from these graphs. 4. How did the researchers address the problem described in question 3? Do you believe that their method was adequate? Justify your response.