Do solids have intermolecular forces?Watch
The forces between the molecules (intermolecular) are weak and break when melting.
I've just made a video that might help also read below
First off not all solids have intermolecular forces. Intermolecular (between molecules) is like international (between countries). So for there to be intermolecular forces you must have molecules.
Molecules are substances with covalent bonds. So things like table salt (sodium chloride) and metals do not have intermolecular forces because they are not molecules. Sodium chloride has ionic bonds and metals have metallic bonds. They bonds are not covalent so they are not molecules.
Most simple covalent substances have low melting/boiling points because they have weak intermolecular forces.
To melt a simple covalent substance you must start to break some of the intermolecular forces not the covalent bonds.
The same goes for boiling. No covalent bonds are broken.
If we consider H2O, water. When it is ice it is H2O with lots of intermolecular forces. The hydrogens are covalently bonded to the oxygen.
When we heat it and turn it into liquid H2O the covalent bonds are still there. It is still H2O however there are now less and weaker intermolecular forces.
If we heat it more and turn it into a gas there are now even weaker intermolecular forces.
P4O10 is a simple molecule so will have weak intermolecular forces so a low melting/boiling point.
Some simple covalent substances are solids at room temp but only if they quite large.
Giant covalent substances are all solids but they consist of millions of atoms all covalent joined together.
Hope this helps