Although 2,2 - dimethylhexane has a molecular weight of 114, no peak is observed at m/z = 114. The base peak in the mass spectrum occurs at M – 57. (a) Draw the fragmentation responsible for formation of the M – 57 ion. (b) Explain why this cation is the most abundant ion to pass through the spectrometer. (c) Explain why no molecular ions survive long enough to be detected. (d) Can you offer an explanation as to why the M – 15 peak is not the base peak