- Gravity, though very weak, is acting between them.
- The neutral charge means the electromagnetic force between them can be ignored.
- The range is too long for the strong force to be involved.
- All of the above.
This is College Physics Answers with Shaun Dychko. If a hydrogen atom is not ionized that means there's a proton in the middle which is positively charged and it's surrounded by an electron which is negatively charged and there are two hydrogen atoms. So gravity is going to act between them as it does between all masses but it will be very weak. These atoms are neutrally charged no charge because every positive is compensated for by the same number of negatives. So there's no electromagnetic force between them. And the strong force only applies on the scale of the size of a nucleus and so it will not exist between these atoms. So all of the above is true.