Sulfur.
there’s no neutrons and 16 protons
A chemical change affects on the molecular level of matter, which makes it irreversible. Combustion is a pretty good exmple. Physical changes are reversible and dont alter the formula. Hope this helped!
Answer:
I know that Aerogel is the lightest metal in existence, but I don't think it would help much with your answer. I mean you can give it a try?
The answer is B, Let me know if you get it right!