Dinitrogen monoxide (n20; nitrous oxide) is a greenhouse gas that enters the atmosphere principally from natural fertilizer breakdown. some studies have shown that the isotope ratios of,5n to mn and of l80 to i60 in n20 depend on the source, which can thus be determined by measuring the relative abundance of molecular masses in a sample of n20. (a) what different molecular masses are possible for n20? (b)the percent abundance of mn is 99.6%, and that of 160 is 99.8%. which molecular mass of n20 is least common, and which is most common?