Explain why methane has a low boiling point?

Oh, it's you again. Alright, Methane is a hydrocarbon and its formula is CH4.

Within HydroCarbons, you've got something called London-Dispersion Forces. And it's a very weak type of intermolecular force. This weak IMF is the reason that CH4 and many other organic/hydrocarbons are either gaseous or liquid. 
The reason it has a low boiling point is because it doesn't require much energy/heat in order to break the weak bonds within the molecule and covert it into a gas. 

Methane is a hydro carbon. It means it contains only hydrogen and carbon. Its formula is CH4. The simplest ans to why methane has a low boiling point is the presence of only one carbon. the higher the amount of carbon, the higher the boiling point. Hope this helps you.