Key words & phrases:C5H10 image diagram on how to interpret and explain the mass spectrum of E-pent-2-ene and Z-pent-2-ene m/z m/e base peaks, image and diagram of the mass spectrum of E-pent-2-ene and Z-pent-2-ene, details of the mass spectroscopy of E-pent-2-ene and Z-pent-2-ene,  low and high resolution mass spectrum of E-pent-2-ene and Z-pent-2-ene, prominent m/z peaks in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, comparative mass spectra of E-pent-2-ene and Z-pent-2-ene, the molecular ion peak in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, analysing and understanding the fragmentation pattern of the mass spectrum of E-pent-2-ene and Z-pent-2-ene, characteristic pattern of peaks in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, relative abundance of mass ion peaks in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, revising the mass spectrum of E-pent-2-ene and Z-pent-2-ene, revision of mass spectroscopy of E-pent-2-ene and Z-pent-2-ene, most abundant ions in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, how to construct the mass spectrum diagram for abundance of fragmentation ions in the mass spectrum of E-pent-2-ene and Z-pent-2-ene, how to analyse the mass spectrum of E-pent-2-ene and Z-pent-2-ene, how to describe explain the formation of fragmented ions in the mass spectra of E-pent-2-ene and Z-pent-2-ene equations for explaining the formation of the positive ions in the fragmentation of the ionised molecule of E-pent-2-ene and Z-pent-2-ene recognising the base ion peak of E-pent-2-ene and Z-pent-2-ene interpreting interpretation the mass spectrum of E-pent-2-ene and Z-pent-2-ene mass spectra of the E/Z isomers of pent-2-ene cis/trans stereoisomers of 2-pentene mass spectra of cis pent-2-ene trans pent-2-ene cis 2-pentene trans 2-pentene C5H10