The primary reason Science Buddies experts volunteer their time is help students with Science Fair Projects as a way to promote learning about Science.
Your question "Can a new Hydrogen atom be created in the universe?" requires more than a little understanding of nuclear physics to understand how it is possible. I provided you with some words that you could use in a search engine to read up on the nuclear physics processes involved. If I used words that you didn't understand, there are online searches that you can use to learn the meanings of those words.
CHEMICAL CONSERVATION OF ATOMS:
In chemistry, atoms are conserved, meaning you can't create or destroy them using chemical, mechanical, or electrical means. An atom has a neucleus made up of protons and neutrons which determines what type of atom it is. Chemical, mechanical, and electrical means will NOT change the neucleus, so the atom will remain the same chemical element.
It is only with nuclear physics processes like fision (splitting atoms) and fusion (combining nucleus of two atoms to form a different atom) that the atomic structure and hence chemical atomic properties of something changes.
manch wrote:so does this mean a hydrogen molecule can be created in outer space
You don't have to go to outer space. High energy physics laboratories are slaming particles together that are breaking apart neucleus and generating "alpha" particles which usually eventually end up becoming a hydrogen atom.
The other aspect
manch wrote:hydrogen molecules are not decreasing
hides the question, how can a hydrogen atom be destroyed?
Stars are combining Hydrogen atoms using fusion to produce Helium but stars are also emitting alpha particle radiation. I personally don't think we have enough knowledge the behavior of everything in the universe to have any clue on whether the total amount of hydrogen is increasing or decreasing.
These are very interesting Science questions, hopefully you will be interested enough to study science and become a scientist and be able to extend our knowledge in these areas. Doing a science fair project and learning how to use the scientific method is a good start on this path; however, working in this area of science takes a lot more understanding of simpler things as a basis.