Is google a valid source of finding information for a paper? why or why not?

I think it is but it depends on the teacher. If your teacher has not said you can't use it then I would say you are fine. I would stay away from wiki, most teachers do not like it.

Of course you can use google to find information, but you can never credit google because it is only a search engine, unless it's something like google support and they made it. You can only credit the sources where you found the information on.