3. The mass spectrum of 2-heptanone is shown below. a) Draw structures for the fragment ions observed at m/z 99, 85 and 71. b) For the peak at m/z 43, write a mechanism for its formation from the molecular ion. c) What is the probable structure of the fragment corresponding to the at m/z 587. Please show by fragmentation reactions meaning mechanisms--from the molecular ion, how this fragment at m/z 58 is formed (16 pts). 100 80 8 Relative Intensity 40 20 0 10 MS-NW-0061 20 30 40 50 60 70 m/z 80 Jump 90 100 110