Question

Compare the strength of the bonds that hold the atoms in a molecule together with the forces that exist between different molecules

Answer 1

Hydrogen, ammonia, methane and water are also simple molecules with covalent bonds. All have very strongbonds between the atoms, but much weaker forces holding the molecules together. When one of these substances melts or boils, it is these weak 'intermolecular forces' that break, not the strong covalent bonds.