Question

Why are the melting and boiling points of C₄H₁₀ higher than C₃H₈ or C₂H₆?

Answer 1

The C₄H₁₀ has more carbon atoms and a larger molecular size than C₃H₈ and C₂H₆, so the intermolecular (van der Waals) forces are stronger.
Hence, it has higher melting and boiling points.