【題組】 (A) A) is the mass spectrum of a 3-heptanone sample obtained under positive ion mode showing the protonated
molecular species [MH]+ with a major peak at 114 + 1 ~ 115 (m/z). This 3-hetpanone sample is
chromatographically pure with only a single peak on HPLC. Why does it have a small peak at 116 (m/z) on the
mass spectrum? (4%)