ATOMS , help me solve this , and thx for your help

How can you use chemical equations to predict the products of the reaction you can carry out?

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.