Question

Which compound would you expect to have the highest melting point?

Answer 1

The compounds with the highest melting point is usually the ones with the largest atoms

Answer 2

First of all, you need to determine if it is ionic or molecular. Ionic compounds have higher melting points than molecular compounds. Then if you have to compare same kind of compounds, you will have to find out the intermolecular forces : H-Bonding, dipole-dipole, london dispersion forces. There are a few more details too, but I hope this helps.