For carbon compounds, with an increase in molecular mass, melting and boiling points ____________.

The Van der Waal's force between molecules will increase as the molecular mass of the molecules rises.

The melting and boiling points of molecules rise when Van der Waal's force of attraction increases.

Additionally, due to symmetry, linear hydrocarbons will have higher boiling points than other hydrocarbons with the same molar mass and can be packed efficiently.