I am new to this site. I just want to know that if my question/doubt is of low level, i.e, from high school, is it ok to post it or not?
I'd argue that as long a question requires some thought to answer and the user shows some effort in attempting to determine that thought process, there really isn't such a thing as too low level of a question.
Some questions that don't require some thought (or anything beyond googling the answer) would be things like straight definitions, looking for random numeric values for certain compounds, etc.
The one thing I might look out for in asking a "low level" question is giving the context of how far along you are in learning chemistry. If you don't specify what you know, you can wind up getting an answer thats beyond your current level (ideally, questions will get answers at different levels anyway, but just to ensure you have a better chance of getting the answer you are looking for).