E fa'avasegaina fa'amalama fa'alavelave fa'afuase'i i ni fa'avasegaga se tolu: IIA, IIB, ma IIC.
Vasega IIA
E fetaui mo nofoaga e iai mea e pei o le penisini, pei o pamu kesi. O le kesi fa'atusa mo lenei vaega o le propane.
Vasega IIB
Fa'aaogaina i falegaosimea lautele o lo'o iai kasa mata'utia. Ethylene o le kesi fa'atusa mo lenei fa'avasegaga.
Vasega IIC
Fuafuaina mo falegaosimea e aafia ai hydrogen, acetylene, po'o le carbon disulfide.