A teacher demonstrated the possible effects of acid rain by placing several types of rocks in separate beakers containing a vinegar solution with a pH of 3. As time passed, someof the solutions retained a pH of 3 while othersolutions gradually reached a pH of 7. Which ofthe following best explains this variation of pH inthis demonstration?
A All solutions eventually reach a pH of 7, so the experiment is not complete.
B Vinegar is an organic compound that react sun predictably with inorganic rocks.
C The rocks have varying chemical composition,so some but not all of them react with acid.
D The students should have measured the pH immediately after mixing since acid rain reacts quickly in nature.