Liquid Force Fins What Type Of Force Must Be Overcome To Melt A Solid Or Vaporize A Liquid?

What type of force must be overcome to melt a solid or vaporize a liquid? - liquid force fins

I say "international", but not 100% sure ..
Please help ..

Part 2:
What type of intermolecular forces in liquid water?
I think that hydrogen bonds?
Other options are: ionic, polar covalent year ...

Thanks