Answer:
good question..... lemme think now LOL
I can tell you're not very educated because everyone knows that breathing pure oxygen for long periods of time can sometimes hurt us. Oxygen in lower levels, such as levels found in atmosphere are just right for us to breathe. Get a life and stop trying to scare young kids that just want help on their homework.
H2O became a vapor when heated because thats the only one that can go back to its normal state, which is what a physical change is.
There are 2 unpaired electrons in sulphur orbital...
