Your teacher is performing an experiment in the lab. She takes a test tube with a clear liquid inside and pours it into another test tube with some sort
of solid. As she pours the liquid, it immediately starts to bubble up, but no color
change occurs. How do we know that a chemical reaction has occurred?

a. bubbles formed

b. the liquid was poured into the solid

c. the liquid mixed with the solid

d. no color change occurred