Help me solve, This is a test, need to explain the answer. This is science

What is the force of attraction between the particles in a salt crystal

Afamily is one another name for a group on the table of elements.

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.