Variable
benzene
2-methylpropane
2-2-dimethylbutane
isoprene
propene
3-methylpentane
o-xylene
ethyne
propane
n-butane
1-3-butadiene
m-p-xylene
2-methylpentane
ethylbenzene
n-pentane
n-heptane
cyclo-hexane
toluene
n-hexane
ethene
2-methylbutane
ethane
cis-2-butene