The pH scale ranges from 0 to 14, 14 most basic and 0 most acidic.
Things under 7 (neutral) is acidic. Highly acidic things are probably lower on the scale, battery acid being 2, 1, or 0 (I'm not sure which of those)
I hope this answered, please tell me if not ;)
The answer would be 502 grams because of the law of conservation of mass, you can't create or destroy mass so then 2 grams plus 500 grams is 502. I am 100% positive that B is correct.
