Halogenated compounds are particularly easy to identify by their mass spectra because chlorine and bromine occur naturally as mixtures of two abundant isotopes. chlorine occurs as 35cl (75.8%) and 37cl (24.2%); bromine occurs as 79br (50.7%) and 81br (49.3%); boron compounds also stand out owing to the two isotopes 10b (19.9%) and 11b (80.1%). for the compound trimethyl borate, c3h9o3b: at what masses do the molecular ions occur? (list in order of increasing mass separated by commas, e. g. 120,122.)what are the percentages of each molecular ion? (list to nearest 1% in order of increasing mass separated by commas, e. g. 55,45.)