Volatility is defined as the ability of a substance to readily evaporate into the atmosphere.
A small chain of hydrocarbon will have molecules in a small surface area. Moreover, a small chain hydrocarbon will have lesser dispersion forces due to which molecules are able to evaporate into the atmosphere easily.
Short carbon chain hydrocarbon will also be less viscous in nature.
Therefore, hydrocarbons consisting of short carbon chains are more volatile than hydrocarbons with longer chains.
