Question

All of the following are signs that a chemical reaction may have taken place in a piece of glass except. a. the shape of the glass changes . b. energy is used or given off. c. new substance besides glass are formed. d. the glass changes color.

Answer 1

All of the choices given are signs that a chemical reaction may have taken place in a piece of glass except the shape of the glass changes. The correct answer is A. This is because it is a physical change.